I have both (and have also owned the TR Custom Reverb).

The Fuchs 30 is cathode biased so is a bit looser sounding, and has less headroom. The "sweet spot" for tone and gain is much more narrow than the OTS. IOW, it's much easier to dial in a variety of great tones with different guitars on the OTS.

OTOH, the Fuchs has built in reverb and buffered effects loop. It also has the option of using a quad of 6V6s or a pair of 6L6's.

I like both of these better than the TR, which seemed tight and harder sounding. in comparision. Harder to dial in.

A cable in the loop makes a *huge* difference in the high end smoothness and response. Different length, different construction are all worth trying. At about 30pF/ft of cable, you are adding a fair amount of capacitance to the signal path.

It's the easiest way to smooth out a D amp without a mod.

That's it....

Difficulty should not be an issue at all with either approach. Both are about as simple as it gets. The cathode cap method does offer a bit more flexibilty.

I suppose you could say that as a general description....i.e. decreased low end response....but I would not go as far as saying you would not hear a difference.

As you mentioned, the cathode bypass caps affect one or both stages and are located at different points in the circuit so depending on what you wanted to do WRT to clean/OD alterations and what value caps you use, they will almost certainly sound different. YMMV of course and the truly curious would be best off trying both.

(FWIW, Gil actually uses 4.7M in his version, the 10M is a non-Gil variation of the theme...)

With the master on 3 the power supply is barely breathing hard, so I would not look at the filter caps as a solution to your problem.

More than likely, if this is one of the newer amps with the 4.7uF cathode bypass caps, your problem can be solved by going back closer to the original design values of 1.0 and 2.2uF. Increased low end response is what happens as you increase the cathode bypass caps.

Try 2.2 or 3.3 in one or both spots and see if it solves your problem. I think 4.7 may be a bit too much in my personal opinion, based on the results I've had with my own amp. (I'm also now getting a bit too much low end with 4.7's.)

If you want to make things a bit easier you can simply tack a 220K resistor to the outside tabs of the pot. That will also make it easier to switch back to hear the difference or simply change the range to a "virtual" 150K or 90K pot by using a different resistor in parallel.

Having tried both fully broken in, I find the EVM-12L to be a far better match for the Overtone than the G12-65. Don't know how one of each would sound, but having at least one EV would probably be better than a pair of G12-65's, although the EV may be the dominant sounding speaker......

That trimmer pot has a *huge* effect on the amp's tone and response.  A quarter turn can be the difference between a very good and fairly bad sounding amp. I suspect some of the people that did not like the tone of the amp when they got it may not have fully explored the power of this trimmer. Ideally it should be re-adjusted whenever other changes are made to the amp.

On my amp the sweet spot is between 9 and 10 o'clock, more like 9:15-9:30. I'd like to see either an access hole on the bottom of the chassis for trimming (of course that would be a significant layout change), or a fine tuning pot on the bottom, like a Fender bias pot, with the "coarse" adjustment set internally and the "fine" set externally. An external pot with the full range of the internal trimmer would be too sensitive IMHO.

For me, it's between 9 and 10 o'clock....YMMV. IMHO, this is one of the first things to establish when someone gets the amp, along with getting the right speakers and tubes.

For a single 12 application, I've had the G12-65 side by side with an EVM12L and the EV sounded better hands down to me. The 65 sounded fine....before comparing it. Tonespotters work well in general with D type amps, but the Overtone seems to really love the EVM even more so than other D amps I've used.

The basic problem is that you've reduced the input signal to the gain stage (with the trimmer)so much that you can't make it up at the output to match the volume of the clean channel. It's a balancing act. You really need to set it up so that you get at least the OD vol you need with the ratio all the way up. The only other way to get a clean/OD balance is to reduce the clean vol. You could possibly increase the gain of the second stage of V2, but you risk changing the character of the OD more than the change you get with the trimmer.

BTW: I also like the trimmer set lower....it really changes the character of the OD in a very nice way, but too low doesn't sound as good to me either. There seems to be a sweet spot.

Fortunately I have a very large supply of NOS and ANOS tubes, so I did not order my amp with tubes. Proper tube selection can make a big difference in the tone and response of most amps. V1 is going to be the most important in the Overtone as it affects both clean and OD tones. Spend time going through various tubes, checking for tone and microphonics. It's probably the most important tube in the amp. Bugle Boys, RCA's, Mullard, and Telefunkens work well here, but long plates may be somewhat microphonic unless you sort them. I've found EI's to sound a bit jangly, and like them better in AC30's than D-type amps.

V2 will be your OD tube, so also go through the same process there, focusing on the range of OD drive and microphonics at volume. Make sure you have your trimmer set properly as that makes a huge difference in the character of the OD. Too high will be harsh. You may want to re-select tubes here if you make a big change in the trimmer.

After that, I often will like a GE 5751 for the phase inverter, but try different tubes because in that position relative balance between halves can make a difference. They don't have to be matched, but they will sound different if they are mismatched from one side to the other.

For the power tubes, RCA 6L6's sound really good in the Overtone, but may not be worth it if you only play lower volume. I've had good results with Tungsol 5881's also. Good NOS tubes will generally sound better and last much longer than new production tubes.

I've played a Fuchs ODS for years using a 2x10 cab that I preferred for that amp after trying all the typical favorite 12 in D type recommended speakers.

For my OTS, I had two baffles made for my combo cab; 1x12 and 2x10. Going through the same exercise, and even using the same speakers as the ODS, I preferred the EVM-12L with the OTS over all others.

Speakers are incredibly important with these amps. I'd suggest optimizing your speaker before doing any other mods to the amp. You may simply be compensating for things you don't like about the speaker, rather than the amp.