As long as it mates to the Mag head instead of to the body, the actual host should make no difference as the two heads are identical at the bezel end.
Personally I'm considering a MOP for my upcoming ROP LE, using one of the non-stock reflectors that pulls closer to the bulb. I do need some throw, but I don't necessarily need a tremendous amount of it, and there are times when a flood is useful too... but the more I think about it, the less I'm willing to put up with a donut hole or having to refocus the light. Hence, I need a compromise. I might even consider HOP or LS but that might not leave me with enough throw. I really wish I had something to compare against... guess I'll just have to grab more than one.
As an aside, reflectors that fit the bulb better, like the M2 for instance, probably get worse with artifacts simply because more of the light is being reflected. More of the bulb's image projected forward = more of said image's artifacts becoming visible. You're getting a brighter beam with more throw, it's just not as pretty.
Realistically, though, will you actually notice if the hotspot is misshapen during everyday use? As long as what you want to see is lit up, and you care about seeing it, beam imperfections will probably be the farthest thing from your mind.
Finally (I know this post is very random, and I apologize) can anyone describe how orange peel and stipple compare in terms of flood, throw, and light transmission? It's pretty clear to me that heavy stipple is much more diffuse than HOP, for instance, but how can say HOP be compared to LS? Is the stipple just the next step after OP or does the texture behave differently in some way, creating a different compromise between beam smoothness and throw?
