I agree about saved searches: needs a lot more work. My biggest peeve is that they can’t be favorited/starred or moved in the account position so they sit at the bottom of everything. It makes using them for commonly used searches pretty useless because they are pretty much guaranteed to be offscreen unless you go looking for them. For example, I want to keep a folder of unread messages from the last 3 days, but without any mailing lists to help make sure I don’t miss something. But for that to be helpful I need to be able to monitor it without having to scroll past the folder hierarchies for my two main accounts and three shared accounts. So I never use it unless I have a very specific item to look for (ie I get an email from someone saying I tried emailing you two days ago, but got no response).
if Smart Folders are in fact Folders, they should be treated just like other Folders. If they are only Searches, then they should at least be easily found on the Search view.