People don't give KT enough credit, in teamgames it can still do a job. Backed up by double repair truck it's a pain to deal with. Especially on urban maps when you can poke it around shot blockers and drain MP or fight a pershing/IS-2/comet.
Using the current KT I would say is a fine art, but of course if you play redball express and park it in an open field against a TD wall it's going to die pretty fast.
My point is, if a unit can get shutdown so easily without designated support there's a problem.
The amount of support a 280 fuel unit should require should be less rather than more.
ISU, AVRE, elefant, croc... all these units I would say are slow and need support in varying levels, in the case of ISU even more. So why should KT be any different?
Pershing is the only heavy that can zap around and nuke everything, but most people consider it OP. IS-2 has KT armour with decent mobility but if you give it the maingun of the KT I would say it would be OP for sure.
If there's an issue with KT I would say some of vet is a bit mediocre, spearhead for instance could use a small buff.