I probably have at least 6 mechanicals laying around here. I do like the simplicity of them however at the same time, I wish I had more control over the discharge rate. You can add a component (called a Kick) that will give you some of the features of an APV but why don't just buy a real one if you're going to go that route?
I've always wondered about the whole 'kick' thing. Plus there's soooo much you need to learn about batteries when you get into mechanicals. I've been doing or reading lately...was up til 4am just last night...& a lot of this stuff is just over my head it seems.