I have the m200s with the cardiod caps (I want the omnis!). They're just great mics. I've used them on sooooo many things: classical guitar, acoustic guitar, electric jazz guitar cabs, drum OHs, live main pairs, pianos, strings, etc. etc. Basically on anything and they're never disappointed.
They have a very smooth, rich sound with excellent off axis response. They're hard to place wrong, in my experience, which makes them very easy to use. The high end has a slight lift, but its much more natural than most SDC. They're dark in comparison to KM184s, C42s, and others of that ilk.
I'd like to have some Schoeps for the classic Schoeps sound, and DPAs are amazing in many situations, but my Gefells have never left me feeling like I could get more out of a mic. I do like C42s or KM84s in some rock/pop situations where I want more bite, but you could EQ that in to some extent...easier than EQing it out, IME.
Lemme know if you want to know anything else...these aren't super well known, but they should be...