I want to record erhu, acoustic guitar and various percussions for now and don't know should I get 2 big, 2 small or one of each for recording. I thought that if I had both I wouldn't be missing other one, but then again would the different mics in both sides make it sound odd?
If you are miking the whole thing, trying to capture the stereo image as it is in real life, you should have the same mic for both sides. If you are individually miking each instrument, it doesnt matter.
It's a very vague question unfortunately. All mics sound different too. I've done a LDC (large diaphragm) and SDC (small diaphragm) together on an acoustic and it sounded pretty good. I prefer using 2 SDC but if that isn't in your budget you could get 1 LDC that can do vocals and guitar.