FYI - the alternate tensioner arrived after an excessively long delay. It is ridiculous. The parallelogram (well, not really, since it doesn't pivot) sits far too vertical, which limits chainwrap. Equally of concern is that the B-tension spring (which appears to be a leftover from the single-pulley version of this thing) does nothing other than to cause the chain to slack up when freewheeling.
This one goes back too.
I rather like this Paul tensioner that's on eBay right now, but the seller is away with no return date set. Plus, I'm not sure if the Paul tensioners have enough L/R adjustment - and I don't even know what model this one is. It's certainly not the current Melvin.
-Kurt