o i don't see how this can possibly be unprofitable at nearly $50/day in generated value.
It can be unprofitable if these things happen:
1. Difficulty rises too quickly
Plug different values to this calculator (current hashspeed is about 250 GH/s) and see how many bitcoins you can generate with different assumptions. http://www.taters.net/btcgc.php
2. BTC price drops
3. Hardware breaks
Even building a dedicated mining rig seems hard to lose money on when bitcoins are $1 each. Exactly how fast is the difficulty rising?
Difficulty was rising 13-20% per 2016 blocks since the beginning of the year but the next difficulty increase on probably February 18th is going to be likely more than 30%. The rise in BTC/$ exchange rate lured a lot of new miners.
But he is correct that todays difficulty and exchange rate means that it is profitable.. today, who knows what tomorow will bring.
Im the the same boat, and am seriously considering cashing in ~700BTC and purchasing a HD5970. Its going to cost me $0 real money for a punt... Though perhaps spending that $700 on buying more BTC's would be a better financial decision?
Plug different values to this calculator (current hashspeed is about 250 GH/s) and see how many bitcoins you can generate with different assumptions.
Not 100% sure what this data means, and what Im supposed to plug into it... eg: here's the result for 600khashes (1x 5970) and the 250Ghashses you said..
Current control of network 0%
Coins expected next block 0
Network growth per block 0.014177%
Blocks for network to double 4889.6
Block Expected coins USD Value Network Size
1000 0.11 $0.12 288.075 ghash/s
5000 0.43 $0.44 507.888 ghash/s
10000 0.64 $0.66 1031.8 ghash/s
25000 0.82 $0.85 8651.254 ghash/s
50000 0.85 $0.87 299376.773 ghash/s