At any given volume it’s still more efficient/less effort at the way it puts out sound (aka headroom) with more extended lows and highs and less mids vs the non-coliseum versions. I find the tone of the non-coliseum versions to be better IME, but not as big or efficient sounding. Typical trade offs IME in tone quality vs power
For coliseums I had a iic+ (converted from IIB), 2 mark iii++ blue stripes, no stripe mark iii++ and played a red stripe mark iii++. The iic+/b was by far the biggest/heaviest sounding one followed by the no stripe. I kept for a while the iic+ coli, but sold it later because the iic+ hrg when compared to me still had a better, more complex tone and the megalith beta actually to me actually outmuscled it by a bit (680 plate voltage on it), so no more coli’s for me. Fwiw, the Wizard Hell Razor KT150 also had a plate voltage of 680 and the 250w ‘80’s Marshall Model 2000 (6x6550’s) is 700 volts