I haven't reached that point yet, but I would surely increase my basic credit price and my EL price.
There have been reports of people increasing their prices and, even if they lost a few sales, in total they earned more. In fact, FT prices are the cheapest among the main microstock sites, so your price will not be absurdly high.
About ELs, people said the same. I haven't had ELs lately (I've had very few in total, in fact), but if you often have them, in your position I would raise them a bit, see if they are affected. I believe that if someone would pay US$50, he probably wouldn't mind paying US$60 or maybe 70, but US$100 however might be too much. It is probably wiser to do that on an image per image basis.
Regards,
Adelaide