Slayers info is a tiny bit off. The Mathews web site shows...
The Mathews Monster Xlr8 is a 5" brace and "up-to" 360fps.
The Mathews Monster is the 6" brace bow and "up-to" 353fps.
I have the original 6" x-force and love it. About as quiet and smooth as you can get and one of the fastest and accurate bows out there as well.
If you are going to shoot these short brace height bows, I think a STS device can make a big difference. It will help keep the string clear of your clothes. That is one of the reasons I like the newer x-force bows that come factory with a good STS.
I haven't shot the PSE Omen yet, but have heard good things from all that have. However the big drawback is it does not have an adjustable draw length.
Joel