I had made a simple mistake. I assumed i still had a year left of my existing contracts. This a year long geometric series was improper. Adjusting to the 17 cycles left, a multiplier of 10.36 is more realistic for the original contracts than the 12.5 figure. For contracts purchased thereafter, they will fall between these two boundaries.
so 14(2407)(10.3618)=349171. So an estimated at 28-54% return.
an even better lower estimate would be 14(2900)(10.3618)-364*493, since. after all, it is the earnings that would be declining not the maintenance. So that is 240744 which is below the 272727 initial investment. Woohoo a loss!