I've had my 50w OTS for about 5 years now, and am very happy with it, especially now.
I usually use a Smartulator with a Lexicon delay/Reverb in the loop and a Port City OS 1x12 cab fitted with the ubiquitous Celestion G12-75.
None of these mods are mine, but I thought I'd share them with anyone new and take this opportunity to thank each of the members here who provided the threads that enlightened me- Bluesfendermanblues, Pickmaster and Bluesking

In reverse order of most profound effect, they are:

1) Series/parellel switch on Smartulator.
From THIS thread.
I much prefer the enhanced transparency of parellel mode, and it's simple enough to put a switch on the front panel of my Smartulator.

2) A switchable negative feedback loop.
Outlined HERE.
I've placed a switch on the back plate to the left of the footswitch jack. Mostly I leave it switched out as I like the looser feel and extra gain.

3) This one is probably the simplest, but had a huge effect on my amps tone...Raising the slope resistor.
I had always found the amp a little wooly and often ran the bass control very low. I actually prefered the control I got with the tonestack in jazz mode, but missed the extra gain a bit. Raising the slope to 200K really tightened up the low end and I'm totally sold on the clearer, sweeter voice.
I realise some guys here prefer to lower it, I'd venture that they're predominantly single coil players perhaps, where the extra girth is an advantage, but I'm a humbucker guy who mainly plays funk, jazz and jazz-rock stuff, and I also play an archtop a bit too, so increasing it and clarifing the lows has been a revalation.

Honary mention goes to putting the OD trimmer on the back- very handy! and a very simple treble bleed on the OD channel, which I now use less after mod #3. Both of these pots are mounted in the two full/half power screw holes on the back plate.
Having used JJs for a while I've switched to a pair os Tung-sol 12AX7s and won't go back now either.

So there they are, some great and simple mods, hope that helps someone, though of course, it's all just my opinion.