I think both Allen and Delonte can add good things in the starting lineup. Delonte can be that kick out option for Telfair to pass to on penetrations (when defenses colapse on him), and Tony is an athletic slasher who can work with well a creative playmaker like Telfair.

And like you mention, having Wally on the bench gives us a veteran scoring presence to hold down the fort with the second unit.
 

I think whether Wally comes off the bench or starts would depend a lot on how him and PP adjust to the new pgs and style of play. If we always need a proven scorer or passer on the court then maybe he comes off. If we need someone to take pressure off PP in terms of double teams maybe he starts.
if the pgs don''t pass much he starts and plays as many minutes as possible.
If we need more defense Tony Allen plays more.