The max voltage of 450V does mean it isn't terribly useful for that role. That and this tubes peculiarities (long warm up time) means it doesn't make a whole lot of sense. Now the KT150 would be fun to tinker with if you like heat...
I for one don't care if you blow up your amp, that's your problem entirely. What I do care about is people reading that and thinking this tube is a sub when it clearly isn't suitable in any way. This amp is supposed to use El34/6CA7 and no other tubes. Not KT88, KT77, 6550, KT66. KT90, KT120 or KT150.
I love the "HS!" markings Kevin put in there...