Sorry to dig up an old thread, but I saw searching for similar information myself. Hopefully my comments will be of benefit to someone else in the future.
I've tried a couple of these options, although not necessarily all of them in a Minimag.
The NX-05 and Fraen seem to be difficult for me to get centered properly. This may or may not bother you. I've got the NX-05 in my Minimag with a sandwich. There's a moderately sized circle of spill, with small square inside it. Inside that, there's a smaller, brighter circular hotspot. The centers of these three patterns generally do not line up with each other, and they move around each time I turn the light on or off. As someone noted above, it is "funky."
The Fraen makes a circle and square, each approximately the same size as the other. Ideally, they'd be perfectly centered, one on top of the other. Generally, they are mis-aligned much in the same way as the NX-05. There isn't much spill to speak of, but the hotspot is quite a bit larger than with the MX-05. It is not like those super-tight "moonbeam" optics, like those seen on the old Inova X1 or the River Rock 2AA/2C lights. I like the Fraen optic, except for the difficult in centering.
I tried an IMS17, but I am concerned at how tightly it seems to fit over the Luxeon's dome. I'm afraid it's going to lift the dome some day, and I'm going to get a bubble. I've never heard of this happening to anyone, however. I can only assume I'm worrying about nothing.
I got my first McR-18 today, and I love it! This seems like the perfect reflector to me, at least for small 1" lights. I'd say it's well worth the money. Highly recommended.
