I feel the main aspect of MFI lending affected by demonetisation would be the impact on asset quality. I think most of the lending of MFIs can be termed as unsecured. (although the companies claim about joint liability group lending etc. ) And hence I would be watching for a quarter or two to see how the companies are affected in terms of asset quality by DM.
Regarding companies getting attractive after the recent fall its all about relative attractiveness. If a stock falls from 200 to 120-130, there’s no reason to assume it cant fall to 100 or below. Its like catching a falling knife. (with not too sharp blades but some edge which can atleast cause minor grazes). I would like to watch the prices of these companies to stabilise before taking a call.