I started to reinvest for about 2 weeks, and then I switched to cashout. After about 8 days now I got about 9% back. The calculation on their own page said ROI in about 60 days if I remember correctly when joining. But if this continues I guess it will turn out to be about 100 days, which I think is acceptable.
I will cashout for some time now before starting to reinvest again. If and When I get my investment back then I will turn on reinvestment "for ever" (well ok, for about a year to be more exact)
While their calculation is correct in general, it's a bit misleading because it doesn't factor in the maintenance cost. So your 100 days assumption are indeed closer to the reality.