I like the sound this mic gives me with several different mandolins. It sounds natural and very musical.
Previously I'd been using condenser mics, which are often tuned for vocals, with a peak in the upper frequencies. The condenser-mic recordings I made of mandolin were detailed but shrill, harsh, painful at times, and not really resembling the original instrument. I took a gamble on the RM700 as a low-cost introduction to ribbon mics. I was not disappointed - if anything it has exceeded my expectations. When I listen to recordings with this mic, there doesn't seem to be anything missing, at least everything I want to be there is captured, with none of the harshness.
The microphone works pretty well straight into my recorder (Tascam DR100III) though the gain has to be turned up quite high. Adding a preamp of the 'cloudlifter' type would help - I went for a very low-cost option and it seems ok. Even without anything extra, the recordings are loud enough to not have any obvious preamp noise.
The only sense in which it is slightly inappropriate for my needs is the generous low-frequency response, going down to subterranean frequencies, but that is easily handled with a bit of low-cut. The Tascam is helpful in that respect, offering several different settings.
Overall, I'm pleased, I like the sound of the RM700 with my acoustic instruments.