That's alot of give and take in the sidewinder. It seems like a fun unit I'd love to play with for cheap. Watching all the guys on cdf struggle with getting it setup easily makes it less appealing. Then you add no flood tolerance at it gets more so. I actually demoed Edds (he wouldn't let me out of class otherwise) and it was surprisingly easy to use and trim out. It does seem like a cool unit if your ok with those shortcomings. If another one comes up cheap like Forrest's I'd buy it in a heartbeat. I can't justify it at full price.
I also saw someone using the sidekick with their backmounted doubles as the drive gas/ bailout. I thought that was a pretty slick idea.
I wasn't a big fan of the sidekick. I am actually certified on one, and have dove it a bit. I'm told that there is a purge in the CL of the sidewinder now. I was looking at one yesterday. I'm not certain if that was aftermarket or factory. I think you're going to have a huge sacrifice moving to any sidemount rebreather. I would never make a sidemount rebreather my only rebreather. But that's just me.