If You are happy with your Mopho filter then don't get a MF101, but You might want to check it out somewhere (at a store, rent it from Your local distributor etc.) because You may find that the Moog filter sound suits You much better, but that's just a matter of taste. Also You might want a filter to put after the Freqbox to tame it's wild high harmonics (add envelope following and You might get some cool talking leeds and bases). Always think about the combinations and possible connections/interactions between different devices when choosing next Moogerfooger, not just the effect itself.
If You are into sonic exploration and like You sounds on the weird/sick/twisted side as well as a nice tremolo and Osc Out and LFO out to add to Your Moogerfooger setup then go for the MF102. When I first tested a few Moogerfoogers I didn't like the RingMod one bit, it was to sick for me, I bought a 103 Phaser then which I find "too nice" at the moment
![Wink ;-)](./images/smilies/icon_wink.gif)
But as I got deeper into the world of modular synthesis, soundscapes, effects I found that the 102 very very cool.
You might also want to consider the MIDI MuRF (mine arrived last week and I love it). When I was considering the MuRF some time ago I though that it was a "one-trick-pony" just doing some resonant bleep patterns. But now that I have it and I sync it to midi clock with my drums I find it suuuuper cool and it has a lot of potential. If You are a producer/song writer You'll find the MIDI ability of the MuRF to be a great thing in the production environment.
Hope I helped.