If price increases as you say, you're better off cutting difficulty (+ noise + electricity costs + work hours + heat...) from the equation and just keeping BTC, as they will increase each difficulty increase anyways in value as well! 
Mining would only pay off if you end up with more BTC by mining after some time. With current increases, it doesn't look like you will mine 25 BTC within the lifetime of a card that costs 25 BTC right now. Also you have to add constant costs like electricity + work to that equation!
Mining would only pay off if you end up with more BTC by mining after some time. With current increases, it doesn't look like you will mine 25 BTC within the lifetime of a card that costs 25 BTC right now. Also you have to add constant costs like electricity + work to that equation!
So we have two scenarios:
A. I stop mining and keep 100 of mined bitcoins so far for the cost of one month.... and have them worth 200*X$ in a month
B. I continue mining and get to 160 bitcoins in 1 month for the cost of electricity and stuff for the cost of two months... and have them worth 320*X$ after that month
Hard to choose, I think I will go with B?