I've struggled with an Ace kit before (not a T-55 or variant). I would not recommend the kit I tried to anyone. I was corresponding with Kevin Keefe (KKeefe) earlier this week about an Ace modern Russian mortar carrier he was working on. His comments were the same as mine.
I've got both the PST T-54 and T-55 but have not built either one yet (pesky group builds get in the way). I picked up both kits for under $5 from
Alanger here in the US. They look decent enough and I got both for less than what the Ace kit would have cost me at my local shop.
I would rate the PST kits just below Revell quality.
Tread, the Enigma kit you saw was most likely an Ace kit. They do have an interesting line. It pains me to pass them up in the store, but I always pop the box to look inside.