Wow, you guys are amazing, I'd given up on finding this and was going to just stick it out with v1.
Downloading the demo now to see how it is. $69 is a bit steep, but in terms of opportunity cost it's a bargain consider how much time it saves me with my work emails.
98 SE, I'm not sure how it compares to the Apple Mail. I do use the search function a lot, maybe 10-15 times a day, but the main feature I use is the saved search which is what you use to replace folders. You can tag emails into a Category or Status like other clients, and have saved searches looking for msgs with these parameters. The saved search sits on the sidebar like a folder and it can display a count of all or just the unread msgs meeting that set of search parameters. I set up searches for all stages of sales: inquiries, waiting payment, unread payment, ready to ship, service, awaiting return, etc. So I can check at a glance that our fulfillment queue (which is on a separate database) matches up with what I have in email. I use to manually check these entries, which is an immense pain once the volumes increased, but if I don't do some sort of check you lose the occasional order that gets skipped over or read without processing.
It also has the option of grouped threads for emails (not sure if other clients have this), which makes so much sense you can't consider going back to flat chronological view. It's very much like reading an online forum