Do you want to track the pallet number during dispatch also ? if yes then you need HU management if no then you can go ahead with SU management
you mentioned " I need to record a pallet number and carton sub-numbers" could you please elaborate about the carton sub number-- if i understood correctly then you are talking about nested pallet or box or carton if that is so then with SU management we have provision to capture only pallet number (With external range) but we don't have provision to capture the nested pallet / box/ carton. Nesting functionality is only available in HUM
You need to look the overall material flow / operation and make a note tracking of pallet is required at what are the steps (remember 902 - GR zone & 916- GI zone) is NON-SU managed so if you are going with SU management then during initial receipt (902) / after picking (916) you will loose the identity of pallet(SU),Tracking of pallet at this storage type is possible only with HU management