Personally, I found that the TX5 version overall had a harsh chirpy presence to it. The Lead 1 red sounded very similar to the other Lead 1 modes and was very flubby sounding. Even with bizarre bass and voicing settings I couldn't dial in a punchy sound.
The TX4 version overall has a pleasant presence that isn't abrasive yet sits with the rest of the band nicely... it really cuts. Lead 1 red behaves more like the lead 2 modes with less of a scooped sound. I find that the Lead 2 modes are much more compressed (not sounding, but rather in between chord changes if I don't lift my left hand up and rather just slide on the strings, the "eeerrrcchh" sound is very present). I find this a lot on newer Mesa amps like the roadkings and stilletos... but not so much on high gain mark 1's and even the 2 channel rectifiers. Having said all of that, the Lead one is crunchy and responds super nice in the lows (much like the lead 2) but doesn't have the "eeeerrcchh" probably half as much. Aka, it's my main distortion sound live.
I owned a TX5 version and HATED it. Sold it and got an older TX4 version and LOVE it.
