Does KT-88 runs hotter than 6550?

Did anyone ever have premature failure with their Sonic Frontiers Power series when using KT-88 instead of stock 6550? In theory they are inter changable, but KT-88 does run at higher plate voltage (true?) and can run the components inside the amp like resistors or caps harder.

Or it is just a rumor?

I am getting ready to retube my Power 3, don't want to make 16 wrong mistakes. I understand EH KT-88 is the current standard for reasonably priced KT-88 and beats the EH 6550 by a long shot.

Thanks guys.

I don't know the Sonic Frontiers amp, but did you properly re-bias for the KT-88's? Properly biased they should draw similar plate current to the 6550, and not run hot.
JJ Tesla KT88 & EH 6550 seem to generate the same heat in my amp.
I run KT-88S on my SFS-80 and bias slightly below the manufactuers recommendiations. They run hot like all tubes.
I have a quad set of 6550's but didn't get a chance to try out. Check bias about every couple of weeks anbd you shouldn't have any problen.
I have a SF Power 2 w/KT88s and haven't noticed any problems. I have corresponded with the designer of these amps about upgrades and one of the recommended upgrades is to switch to KT88s. He claims an approximate 15% power increase and they sure sound nicer to my ears.