Don't worry about the SdKfz 252s. Those are part of my SdKfz 250 set.
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You would have to talk to Don about what other vehicles he opted to go big on. But if I had to guess, I would say, yes, they would probably work with current Tigers and what not. I know the Pz IIIs are a bit big, because those are mine and I did those before I knew of the 1 pixel = 6" scale. Those are actually how I got my personal scale. I liked them so much I didn't want to shrink them...LOL. Those are actually 1 pixel = 5.5". But, those are in the works to get redone in the proper scale too.
Oh yeah, I have already built both of the Tigers with variants in my scale. But again, to be released here I have to rescale them. I could give you a sneak peek if you like via pm? I won't put them on here, because I don't want people to break them done and use them in their game if they are too big.