I have seen a few projectors over the past month, and the 750i was easily the best picture I saw in my price range, which is about the same as yours. I was close to pulling the trigger, but a couple of things held me back.
First and most importantly, and this sounds like it may be an issue for you, is the light output. From what I have heard and read, you should not be using the pj on screens much larger than 100 inches diagonal. At 120, you are pushing things to the limit. On a 100 inch screen the image looked terrific. I am starting from scratch and need to build a room and buy a screen, so I am very flexible. I would however like about a 120 inch screen.
A second less important factor for me is the 750i does not do 3D. While not critical, if I am spending all this money on everything, it would be nice to have the ability to watch 3D on occasion.
I haven't seen the Sim2 M150 but it sounds like it has exactly what I would want. Unfortunately its double what I am willing to spend, and it sounds like its too pricey for you. Maybe one of their lower end models (eg M50) might be an alternative.
If you are a Runco fan, the x200i should be coming out around now, and while the list price is a fair bit over your target (15K) , hopefully you could get one for just a couple thousand over your target price. That however might not be what you want since its is not LED, and you are paying for 3D. Based on the press releases , it should be a good fit with your screen size. I will be looking at that one when I can.