I think there's lots of good KT88/6550 amps out there already, and they're more limited in power. I think the high powered KT150 fills a gap, particularly for people with more power-hungry speakers (ie, the vast majority of people).
In addition to the models already mentioned, I found this Italian-made design offering 30wpc from 2 x KT150's:https://www.gabrisamp.it/negozio-online/nuovo/calypso-kt150/
This goes for $2,500+ (equivalent) - as another point of comparison.
It's pretty big (380mm x 460mm x 210mm).
Quite heavy at almost 60lbs (27kg).
& Doesn't offer Triode/UL switching either.
The projected specs for the Wolf Ear seem more attractive to me.
More versatility, lower weight, etc.
(Just my impression, I'm not making any assumptions or claims about the sound quality of either product.)