I'm probably in the minority here, but I don't think that the Church Audio and Audio-Technica mics are "light years" better than the CSBs. In fact, I think that they sound much more similar than different. I think that a lot of the difference is due to the fact that the CA and AT mics can have cardioid patterns, but the CSBs are omnis and the CSCs are cardioid but sound awful. It all depends on how you use them and on what capsules you use. In my view, the only mics that are a significant step up from the CSB, AT, and CA are the dpa 4060/4061 and Countryman B3 (I haven't heard too many Nevaton recordings), and those cost two to three times as much as the other three options.
For the open-air music festivals that that the OP says that he tapes, the CSBs may be better than the other two options because he does not have do deal with the directionality and frequency response issues of a club. At least I always prefer the sound of omnis outside to that of cardioids; others will have different opinions (and theirs will be, of course, wrong).
Stealthing presents a different sort of challenges, however. In clubs, cardioids may be a better choice, but you can make perfectly good recordings with omnis if you can roll off the bass and process the recording a little bit afterwards. In arenas, cardioids are definitely the better choice.
I would suggest looking on DIME and etree for recordings made with the various microphone choices and in recording situations similar to the ones in which you intend to tape. After listening to them, you can approach the situation with more information.
Personally, if I wanted to throw a little bit of cash at the problem to get "warmer" recordings, I would keep the CSBs while selling the CSCs and the recorder, and pick up a Sony M10. The M10 has a good microphone preamplifier, an excellent A/D converter, and would likely be a warmer-sounding device than the current recorder. If you have your heart set on keeping the recorder, you may want to see if you can pick up a Church Audio preamplifier instead.