Thinking of replacing my Bat spaceheater with class D, real world thoughts please

Class D makes big power at low cost. It is this factor and this factor alone that compells manufacturers to adopt this topology. Yes, some can sound decent but replacing a BAT tube amp?... If your amp is causing you to sweat, you can move onto good Class A/B and not miss much in the way of musicality.
If you can’t tell a difference between Class D and A/B, time for a hearing exam.

I can't make a firm suggestion unless I know what speakers you have and how efficient they are. I am not a fan of BAT and you could certainly have a much better tube amp. Forget the class D. 

Sounds like it's high time to begin doing some 'blind hearing tests' on D vs. 
'anything else'....

D will win eventually, if only by sheer weight of numbers and application.  I'd bet on this, but I sincerely doubt I'll live long enough to witness the end of the 'contest'.  A, A/B and all will live on, but only as 'curiosities',  as those of us who know them well enough succumb to the inevitable.

It's already well known that stasis is self-defeating.  You either grow, or you will die.  You can only adjust the span, not the outcome. ;)

Get behind the new tech, and make it become what you want.  Put your dollars where your interests lie.  It's always worked before...look at the thing you're typing into for an obvious example....;)

Been there --  the  simple answer at least for me is  --- Ive wound up relegating  the class d for duty in hot weather.     I wouldn't be in a hurry to sell your BAT although that sounds like a bit of heavy weight and likely equivalent good listening could be had with an amp that weighs half as much or so.    I would have to see what model that it is and if its  tube ,  in my experience,   that Class D will not be as satisfying as the tube or  s/s  class A or A/B amp..   Its a different sound and has it place  and can sound good-- It obviously works wonders as a lot of people go with the class d as main amp.... To me I just seem to get a little more from conventional amplification topologies.     I like to mix em up.   tube amp,  class a/b amps,  class A amp (Pass)    and a Trends for the hot weather-- all used among 2 systems.   A good buy available in the classifieds right now is the PS Audio---HCA 2  or something like that.   Lot of raves on that amp..  Good way to check out class D .   Have fun.  

Oh yeah,   the BAT you have  is a beast.  great  amp and certainly can be fun at times.   I wouldn't be able to run it though like all the time.   .   best thing is switching off  from the smelter   to other amps at times so as not to heat up the house on a summer day.   Thats what I have to do - take a break from the Pass and the BAT probably is warmer.