Retrying Mail.app in Leopard

Earlier this year, I began exclusively using Gmail for my e-mail needs and abandoned Mail.app. After upgrading to Leopard and spotting Gmail’s recent IMAP support, I decided to do a backwards trial and attempt to switch back to Mail.app.
First let’s talk about Gmail’s IMAP support, which I’m not especially pleased with. To get on wireless devices (ie, the iPhone), they had to offer this at some point, but it’s just not completely compatible with the way Gmail works. The most egregious thing I found was that every time Mail.app autosaved a draft while I was typing, Gmail would create an entire new message in the conversation. When I was away from my Mac and looking at Gmail.com, I’d see a conversation that had 15+ incomplete replies from me, all nonsense. (Maybe this is just Mail.app but it’s unusable)
Second, and more importantly, I want to address my biggest issue with Mail.app. Gmail’s killer feature that keeps me sticking with it is Conversations; yes, yes, I realize that Mail has a threads display, but it’s just not the same. Conversations keep me organized and represent a significant increase in efficiency. Until Mail.app can duplicate that, I can’t use it. I can barely use Outlook at work for the same reason. Mail clients and Gmail’s web competitors are simply behind the times until they copy this feature. Mail’s display and information design is pretty, and as mail clients go it’s usable, but it’s not written for straight up efficiency like Gmail is.
Before I get labeled a Gmail fanboy, I’ll address the two features that I can’t stand on Gmail. First, Contacts is borderline unusable for any professional user, even the new version. No merging contacts and lack of metadata points are my two biggest complaints. I’ve got a few thousand contacts that are in my personal and professional life, meaning that duplicate cards are inevitable. But Gmail doesn’t let me merge them. In fact, I can’t even copy the information manually if it contains duplicate e-mail addresses, because Gmail gives an error. In that case, you have to delete the card you don’t want (yes, really), and then paste the missing e-mail address into the card you want to keep. Almost completely unusable.
Second, if I’m to use Gmail professionally, I need additional data points in the Contacts screens. I need a space for URL, to mark e-mail addresses as inactive, etc. Why do I need to mark addresses inactive? People change e-mail addresses, but I still want to associate old conversations with them. But I don’t want to mistakenly e-mail an old address. For a system that’s meant to be a permanent archive of your e-mail and that aims toward professional/geeky users, this sort of detail makes all the different.
I’m sticking with Gmail, but the devil is in the details, Google, and I get the feeling that you’re falling behind.