Byron;
Hi!
I'll take a sort of stab at your question, as this is a subject / vehicle of interest to me, and I happen to have had one of the 4 1/35-scale kits the D has put out on it...
That's right. There are at least 4 kits out by Dragon / CyberHobby on the S.IG 33 on the Pz III hull... Almost funny, seeing as there may have been around 24 of these ever built!
The oldest and first kit is/was the 9000-series kit put out in the late 1990's? Pre- MagicTracks, old Dragon / DML kit. But a pretty basically-sound kit - just link-on-sprue tracks, somewhat simplified and softer detail, etc.
This kit was re-boxed by CyberHobby as a "Value" Orange-box kit with a set of Magic Tracks and some figures tossed in - pretty common on the markets and eBay. Same old kit, updated tracks, maybe a couple of added PE bits (this is the one I had and recently sold at a model show...

). Often available for a relatively lower price.
Both older kits are curb-side only, and have no real detail inside the compartment.
Dragon did a new-tool kit a couple years ago - Magic Tracks, new hull tub, new hull top, some interior details and a complete gun... modest PE... a completely new kit. Said to be pretty nice; this kit represents the earlier in-use period and has feature, such as rear boxes and spare wheel mounts, as reputed to have been seen on those that went to Stalingrad area in 1942.
And last year, Dragon released ANOTHER modern kit of this vehicle - this time representing the later in-use period from ca 1943 - different fender details and spare wheel mounts and different rear box bits (I think). I think this last, newest release has DS tracks...
I have NOT seen or handled sprues of either of these newer, modern-standard kits, but all reviewers have said that they are of course modern: crisper details, better molding, many more parts, some PE, etc. Folks seem very positive about these newer kits as both good modeling and being pretty accurate. Having the newer Pz. III tracks and road gear would be a real big improvement over the older kits - the boxy and rather simple upper hull may not actually be much different between newer and old kits... The complete gun would be nicer if you like the interior aspects. I would still probably add an AM metal barrel if a metal barrel is not already part of the newer kits.
I keep intending on getting one of these - probably the 1942-era kit, as I prefer Magic Tracks - but have not come across one at a good price... yet!
But, to be sure, I've seen many very nice builds done with the older kits, so it can certainly be done - again, by me, the improvement places would really be the running gear aspects - better and more-detailed road wheels, etc. So, depending on money and "needs", you could probably be pretty happy with any of the 4 kits!
Google the kits and reviews!
Bob