Well, just to follow up on this, it looks like all of the internals are the same between standard and takedown models. I ordered exact edge extractors and upgraded bolt buffers, mainly just to improve reliability. As far as the mag release, the new version is night and day better than the older, flush style. I think I'm going to stick with the factory setup on it. Once I get the opportunity to play with a tactical innovations type release, I may upgrade the older ones.

I won't get a chance to shoot the TD until the 2nd week of Feb, but after playing with it for awhile, I like it. I took the adjustment screw down to 3 clicks instead of the recommended 2 and it locks up very tight now. I actually had a bit of a scare when I did it. I tightened it down and then put it together. Then I couldn't get it apart! It would start to twist apart but then just stop.

I was dreading the call to Ruger to figure out how I screwed it up, but then realized I'd forgotten to lock the bolt back.