HTC could make use of the SdKfz 251 in a number of ways. For purposes in AH, they could use a mortar version (something not currently in AH), the infantry support gun (very similar to the LVT4), the AT version (75mm AT gun with serious AP ability), an AA version with triple 20mm (faster than wirby, %25 less firepower, yes slower than M16 and more firepower than M16), and for EW use the3.7cm or 5cm AT gun would be nice to see as well.
The SdKfz 251 is a very capable gv, but the #1 use for it (carrying troops) is over shadowed by the M3 due to speed.