I've never noticed any interference with the mics rotated but I always have the stand behind, not beside, the mics when recording. So far it's been just nature sounds except for taking that setup to the nearest railroad tracks to get trains as they pass. Won't use it for music for another week or so where it won't be my primary rig. I'll do some critical listening after that show and hope I can't tell any difference between the two rigs.
For stability, on top of the stand makes for a more stable setup. I need a larger base as this small desktop stand base is less than ideal even with the extension at it's lowest height. I have mounted the mics like this on a regular light/mic stand and when the mics are postioned directly above one leg it's very stable and I wouldn't worry about it even in a crowd.