People have bad mouthed RF since the begining of time and they have had a couple years of bad amps. I wouldnt get a Prime series as they suck and I wouldnt get any of the Punch level 4 channels but their Power series is still solid and their Punch series 2 channels and mono blocks are still good. Their mono blocks are some of the most efficient in the buisiness.
Now on to your mod. What exactly did you do to mod your amp to unregulate its power rail and increase the DC of the FETs?
Yeah when their Thunder and Black Gold was re-introduced in the early 90's they made some great great amps. Very basic but uber clean and put out double their ratings. The amps were just solid black bricks with very basic x-overs and bass eq's. I had a 4300 and 2300 that were both built for MTX competition cars. They had .5% tolerence components and MOSFETs that could pass double the original current over the regular production ones so they really really slammed! I bridged the 4-channel to drive my OZ Audio and Infinity EMIT (old rectangle ribbons, not the current BS) and was showing 490 watts RMS per channel!

With the 2300 driving some Phoenix Gold CF 10" subs and I clocked 143.2 db which was insaine for the mid 90's.
Anyway, thats when some guys from Rockford went over to MTX with Rockfords next gen specs and made the amps.
Now MTX is not about purity like they were and became soley a profit machine.
There are very few purist companies left. Even some of the new Boston components are crap. All thats left for all out quality is Rainbow, Focal, McIntosh, Butler, some MMats, upper model JL, Nakamichi and some others. Used to be about being the best, now its about being the biggest.
Its a shame cause really people are loosing out. Sure there is a crap ton of DECIENT sounding stuff out and with this age of iPods and computer speakers and speaker sets that make your phone a boom box has gotten people used to mediocre sound.
Man, you take some kids iPod and load it into an old NAD preamp running through an Audio Controll 1/3 octave EQ into a McIntosh real tube amp driving a set of Beta IRS-V speakers and they will be blown away! Can hear every nuance in the music, can hear the lead singer taking a breath, a guitarists pick striking the strings, the drummers stick accidentially hitting the rim of the drum during a drum strike....... sorry, love music and love it when it sounds exactly how it is supposed to.