Ya'll

Trying to decide whether to get an Expression or Liverpull.

Seems to me that I should get the Expression as I can always bung some yellow jackets in there to convert it to EL84 to get more of that tone.

Anyone tried this? Are the tubes the only difference between the two, or are there major component variations?

There are tweaks in the Tone Stack and Presence control between both amps, in the Expression to invoke the spirit of a hot, responsive Marshall and in the Liverpull to invoke spirit of a hot, responsive Vox (as opposed to the more tradition Vox tones of the Rock-it).  But they are extremely similar preamps.  To me, the voice of the amp is in the Tone Stack, not the power tubes used.

As noted the Expression can run 6V6GT's and the Liverpull can run with half it's power tubes turned off, each for a pseudo half-power option. 

First I've looked at a T'wreck in a while, never realize there is an entire triode not utilized.  One half of a 12AX7 that will be brand new long after the rest is worn out.