Sorry I did not see your post until today. I am a live sound audio engineer by profession. I have done thousands of orchestra type concerts over the years and tried lots of mics on strings. Mics that may work well for recording often suck for live work. The general consensius amoung pro live audio engineers for Cello mics is the DPA 4099C
Nothing out there comes close for live sound. But I have had good (as opposed to fabulous) results with AKG 747 mini shotgun (3ft away). You gotta get the mic close to get all of the tone & these do the job without interfering with playing the instrument. Also good GBF.
Most anything less pails in comparison. You get what you pay for.
Micing instruments for live performance is truly an art form and has as many opinions as there are people.
Hope this is helpful.