Profitability depends on how long you are willing to wait and what you mine with.
Well I don't just want an answer to myself... it's good to talk about these things. Let's say time frames are 1 month, 6 months, 1 year, and mining hardware are either GPUs (Radeon R9 290X x1) or SHA256-capable ASIC miners. Let's assume 700MH/s for the first and 4GH/s for the second. Since I don't expect a straightforward answer right off the bat, how would one go about calculating profitability under these scenarios?