From my spreadsheet, I use =24/(Difficulty*2^32/10^12/60/60)*25 for the BTC rate, which currently gives 0.00281463. Yeah, that formula could be greatly simplified, but you get the idea.
To make the math easier I mostly figure the pool fee and earned transaction fees to cancel each other out to within a few tenths of a %. That leaves me:
Nicehash 0% = 0.00281463*0.97=0.002730191 (0.27)
Similar results. I too am now using a long term 107% number, though I do notice that is trending upward.
I have fixed orders at 0.0028 and 0.0027 to anchor a good spot in the order queue, and I have several floating orders that my bot moves up/down between 0.0025 and 0.0030 to maintain a average rate.
At 0.27% of the pool for 90TH, I have a 1 in 370 chance of being a block finder. Assuming about 150 blocks per month (1 in 75 chance of a block find hitting a prize), that is a (1/370) * (1/75) [a.k.a. 1/370/75] = 0.0036% chance of hitting a prize (1 in 27,750). That is the back of the envelope version. I don't really consider those odds into any of my decisions.
but if you increase to 180 th only during a high cdf spot the math helps much better to win high cdf then the steady flat number of 90th.
I have 25th-28th in real gear here. It stays.
I spot rented on some of the high cdf blocks below.
752 406348 25.49482709 2016-04-08 21:00:35+00 Matured 578,233,238,077 346.556% 0.969 36 - I got 6 blocks on this rental
745 406042 25.38250979 2016-04-06 17:05:10+00 Matured 432,475,516,451 259.198% 0.925 43 - no spot mining
736 405758 25.35573784 2016-04-04 20:24:36+00 Matured 824,764,252,251 494.310% 0.993 52 -- I got 10 blocks on this rental
726 405383 25.35108456 2016-04-02 08:12:57+00 Matured 424,062,913,997 254.156% 0.921 62 -- no spot mining
this is our high cdf guy belowBlock #745 e46btc with a CDF of 0.925 (259.198%) at 2016-04-06 17:05:10 UTC
If we get to 250% I will spot rent again.
The high cdf part of the game really is cool as it does encourage more rentals from a guy in the 1th to 100th range
the low cdf is also clever as it discourages insanity at playing too much during a high cdf spot.
I believe this is why kano has both prizes. Note I pulled my quotes out as kano does not like tons of quotes.