I have the solid C-moly on a MM and also had them on a Viper. I trashed the ones of the Viper and replaced them with the Alum / C-moly.
When I switched the Alum / C-moly I should have also ordered replacement tubes at the same time. I have since bent/tweaked one of the Alum tubes and tried to order a replacement but was told they where out of stock and they had no idea of how long it would be before they were available. I ended up just making my own tube, I have a machine shop full of CNC machines so it was easy to do.
I built a mod sled for my nephew and he chose Fabcraft TA's and know a few other guys who are runnnig them. They're a little more $$$ but they support the product, plus they're great people to do biz with.
http://www.fabcraft.com/trailingarms-yamaha.php?sled=19