Just out of curiosity...are you guys still mining GPU? I literally just put together my first righ a month or so ago, so I was really late to the party. The catch is, I have free electricity....so I was contemplating throwing another GPU in and getting about 500khash extra for around $400, but was wondering if that is worth the investment...I mean free electric is great, but not if the KnC Titan or whatever the hell it is comes out drives the difficulty so high that any GPU is screwed.
First of all, 500 khash for $400 is a terrible rate, you're buying the wrong GPU in that case.
The KnC is advertised to be done Q2 or Q3, so expect Q3, which will be quite a while.
But basically, don't listen to advice about this from a stranger on the forums who probably has financial gain in giving bad advice.
Instead just run the numbers. Look at current profits per mhash and project how long it takes to get ROI.
Then run the numbers again with a worst case scenario by projecting the downwards profit trend from the past few weeks into the next few months.
Personally, even at free electricity, the ROI is probably too long to bet on what currently seems a consistent downwards trend of profitability.
But don't take my advice, run the numbers yourself, estimate possible profit and then only buy when those numbers look good to you.