Yes please, bring back Delete Upon Reply!
This is one of my most severe disappointments with v5, and the former feature I miss the most. The idea of an efficient workflow is to process each item only once, keep track of it in a single place, then forget about it, ie: turn an email into a task or appointment and delete it from the mailbox. Now I do have to do more work than before and process items twice. First to address it, then a second time to find again the original and delete it.
What I want to do is process emails efficiently, deleting a maximum of mail after processing, and to only file a minority (as small as I can make it). It seems to me that v5 is going in the opposite direction.
I'll try v5.0.2 for a few weeks to see just big the annoyance is, but this will probably be reason enough to downgrade to v4.