If the smaller/compact cooler running amplifier is very 'close' in sound quality to the larger hotter amp I could probably live with that compromise. However the performance gap would truly has to be quite narrow.
I want to be able to enjoy and get emotionally involved with my music to the best of my ability (Isn't that the point?). If larger and hotter amp means clearly better music listening experience and long term happiness then bring on the heat and additional size. Sound quality is the prime objective.
Charles