please check all details before making such comments.. You are free to mine anywhere, however please take in mind taht:

best profitable xoin at this very moment (changes every minute is UD 1.50/day):
http://www.coinwarz.com/cryptocurrency/?sha256hr=1000.00&sha256p=500.00&sha256pc=0.1000&scrypthr=1000.00&scryptp=500.00&scryptpc=0.1000&scryptnhr=450.00&scryptnp=0.00&scryptnpc=0.0000&x11hr=4000&x11p=0.00&x11pc=0.0000&keccakhr=500.00&keccakp=0.00&keccakpc=0.0000&quarkhr=450.00&quarkp=0.00&quarkpc=0.0000&groestlhr=450.00&groestlp=0.00&groestlpc=0.0000&sha256c=false&scryptc=false&scryptnc=false&x11c=true&keccakc=false&quarkc=false&groestlc=false&e=Coinbase
The 2nd best is 0.80 USD/day

We mine different coins with a higher profitability then darkcoin (one reason is, better payouts, ohter reason is diff is way too high, even for multipool)

If you calculate your revenues back to USD, take in mind that the sync we paid you varies ever 30 minutes with very high min/max difference)
https://poloniex.com/exchange/btc_sync (check last 2 days)

It is almost impossible to make good stats in USD, therefore we list in our site the BTC/MH/day (currently just between 0.0007-0.0010 BTC/MHs/day)
If sync is dropping after we purchases, or after we paid out and you check exchange rate 24 hours later, the whole picture is different again.

As said, please mine wherever you want (preferably at the multipool) but don't decide about this on a too simple mathematics..