Well, one advantage of the new PM system is that each "conversation" only counts as one message in your Inbox, regardless of how many actual messages that conversation consists of. This won't help with existing messages that are converted over, since they are all individual "conversations", but it will help with any new conversations you start.
Growl! I'm nearly always at the end of my message limit because archiving images and attachments doesn't happen without me manually stitching it back together on my hard drive. The joys of working in teams homebrewing . Any chance developers can have bigger PM boxes?