I can understand your thought. I used turbo in other ID's and it was good for alot of things, unitl I fould Auctiva. Your right, Auctiva is Web based, so it has its slow times, but I list at odd hours, late late night or eary am. Then I save my listing for a scheduling when its busy on Auctiva. I think lots of people list and post at the same time, so the bandwidth is narrower.
I think If you had to, you could try and design an Auctiva ad, then save the Html code and paste it to Turbo and see it it works. Let me know.
Personally, I'm personally vevy happy with Auctiva and their customer service and really like the community here. I too look forward to the new version coming in July.