If you are using the folding stock, I would get something that is lower than a standard AR mount, and just keep the irons folded when not in use. Standard height AR mounts put an Aimpoint slightly too high on an XCR, in my opinion. It would probably be best to try first.
Yep, I've got the FAL style folder. The consensus seems to be go low in order to afford an optimum position for the optic which is the most important issue. What are your views concerning the Aimpoint mount vs the Larue mount? Does either system place the optic in a better position on the XCR than the other?
If you get the Larue ring, just make sure you get the one that is designed for the "on the hump" RAS rail for the AR. That one will put it lower on your XCR than the standard height rings. That is the one I would get if it were me.
I use Burris 3/4 inch tall rings which places the center of the optic 1.34 inches above the rail. This makes for an almost direct co witness and lets me get a pretty good cheek weld. I just ordered some Larue QD rings which place the centerline at 1.28 inches. This will put my co witness closer to the top 3rd, but I doubt I will notice the 1/16th difference much. Someone in this ball park works well for me with a red dot with or without magnifier and magnified optics.
Thanks for the input guys. I'm going with the Larue package deal, Aimpoint ML3 & QD RAS II mount. I'll probably end up going top drawer on the backups as well and mount Troys. Tried to save some coin and got the Promag GG&G knockoffs last week. Took the weapon out for the first time on Friday and could not get zero at all, way low @ 50 yds. The front post is the problem, sits way to high in its lowest setting, probably a machining issue. They are going back today. Cheaper Than Dirt has a liberal return policy thankfully. Lesson; don't go cheap!
My Troy's front post has to be bottomed out to get on target at 100 yards. I think it may be something to do with the height over the bore, but not really sure. Bottom line, they are a backup, not even close to precise even by iron sight standards, so as long as they can help me hit a target at 100 yards if necessary, and fold out of the way when not in use, they work for me. If I had to crank the rear one way to the left or right, that would worry me more.