I hope everyone joining this group buy knows that they'll NEVER break even.  Assuming the difficulty slows down to its lowest increase in a few months, the most recent of 20%, with an April 30 start date, you'll only recover 73% of your investment by year end.  I would never use coinwarz for an estimate as it doesn't calculate based on the difficulty increasing every 2 weeks like it does.  At this rate, the difficulty at start, assuming 20% difficulty increases, will be 7827M.  These calculations for this post are based on http://bitcoinwisdom.com/bitcoin/calculator with 2.99% pool fee to account for slush's 2% and the OPs 0.99% management fee and using the 15 GH/s rate. you'll pay $69 today and still have $18.49 left to recover 1/2/2015.