I've been using a Thunderfunk TFB-420 along with a 12/6 for a couple of years. Thunderfunk + fearful is a very good pairing. Keep in mind, there's some compression on tap in a Thunderfunk.
A little compression changes the Watt needs pretty dramatically, but going from 2,000 Watts to 600ish needs some live testing to know if it floats your boat. Not everybody likes compression, plus, the Watts you need may not be anywhere near what you have on tap now. Frankly, if your rig works, my first thought is don't mess with it.
My own context is very different - I play a mix of blues and jazz at levels to match a normal un mic'd drummer. I like a bit of compression even at those levels - helps make a round tone that fits in a mix nicely. The pairing has amazingly usable eq - I can smash even the most difficult room into submission quickly.
Can we play outside?