I guess it’s a case of relative. 8 to 70 is truly dwarfing. 8 vs 20/25 may not so much. I think pawpaws look great just as trees, so I try to leave them as is. Then again, I care much about pawpaws so I don’t invest much effort into the harvest process.
The local pawpaw growers association rep just lets them fall and then collects to harvest. Another NaFex member here has strung up netting about 2-3 feet off the ground to catch them as they fall without any bruising.
I think @TrilobaTracker meant about the fruit not necessarily about the tree itself. The fruit can have a tendency to crack (pretty sure it’s somewhat cultivar dependent too) when exposed to too much sun. At least that is what some of the growers association have said. It’s also speculated that it may also be due to fungal reasons, but we get cracking here without any Phyllosticta fruit spot, so I don’t know.
That said, usually pawpaws that are in full production and produce good quality fruit are lush and full of enough vegetative growth to shade the fruit, so it’s usually a moot issue.
If you have poor quality soil though, the pawpaws like most other things will kind of peter out their growth and become naturally dwarfing. All of those “pawpaw trees” come out looking like shrubs more than trees though.