The minimal amount of heat from a class A amp is equal to 4 x 100 watt light bulbs approx. no big deal and since I love the sound I see no reason to ditch the amp becauseof heat, unless one wants a new toy for the sake of a new toy.
The cost of elctricity in my area is 12.5 c per kw hour. Multiply by .4 kw and my amp costs 5c per hour to run. I am more than happy to put another nickel in the slot every hour :)
Maybe class A amps will become more popular when homes are mandated to have non fossil fuel or natural gas heating.
Compared to a 36.2 kw electric furnace .4 kw ain't nuthin.