Yes AI "kill stealing" would happen at times, however I think in a primarily single player game such as the SH series I could cope with it happening on occasions - even against capital ships I suppse!
The benefits of having wolfpack attacks would certainly out weigh the occasional lost kill, no more would I be the sole sub attacking a large convoy with 8 destroyers in escort!
This would also open up the chance to witness friendly subs being destroyed or evading the enemy - knowing my luck an underwater accident woudl like ensure at the first chance I encounter a friendly sub!
V