I have used the Marauder platform to great success this last FT season in WFTF PCP. I have also set up a backup gun using a Challenger with a Huma regulator in it, everything else stock, except for the larger transfer port, and prouder screws to hold the valve in place. Shoots just as well as my TM 1000 and my Steyr LG 110 FT, although much more finicky as far as pellets go. If you need any more details on what I did to mod them, (which was not a whole lot), feel free to ask.
Assistant Match Director
Eastern Suffolk Competitve Airgunners Association
Long Island NY