Panther, I used a set of Mirage resin zimm for my early A. (I think Mirage is the same as Atak.) It comes out very nice, but it's not exactly what I thought it would be.
Here's an old pic -- sorry I couldn't find a picture in my archives of the kit painted. It looks kind of rough, because it's bare plastic and metal --
I had read a review saying that the resin was like onion paper, but mine was of variable thickness. Some of it was amazingly thin, indeed. Like onionpaper! But around a quarter of the surface area was thicker. So I sanded it from the back, and I noticed that if I sanded it too close, individual bricks of zimm would come off of the sheet. And even though I sanded it, the thicker sheets of zimm were brittle when you try to put them around the corners, and it wasn't unusual for the resin to splinter a bit when bent, or if it didn't splinter is went around the corner angle buckled rather than tight, with a bulge around the angle of the steel plates. (Darn those Germans for all those sharp angles!
) I tried heating it with a blowdryer so it would sit down, but that actually damaged the model, as styrene's melting temperature seems to be lower than resin's (from what happened, anyway), so I don't recommend that tactic.
Then again, maybe I just got a bad batch. I'm considering getting the Porsche turm KT set from Mirage (Atak?) and seeing how that is. Or I may try Cavalier and see which is better.
Keep this in mind, but also keep in mind that I am basically happy wuth the Mirage set. They give you decals and painting guides for specific vehicles too, which is nice -- and even some PE parts! I actually found their PE to be nicer than the equivalent Eduard parts, so used them instead. And the resin parts for the mantle and so on are very nice.
(Remember thhough this is all concerning MIRAGE -- if Atak is a different company, then this might only be very general advice.)
One last thing, though -- there doesn't seem to be quite as much resin on the kit as there was worn by the actual vehicle -- some spots are bare which, from what I can see, were actually zimm covered.