My 2 satoshis :
I bought a XMR contract a few months ago on Genesis. It's still doing "good". Nothing incredible, but the ROI is here (I transfer my earnings to exchange sites).
It's a 2 year contract, without maintenance fees (so they can't discard it). I paid $80 and earn about $15 a month.
(and I don't even post an affiliate link

)
Are you counting your profits by the value of XMR or by the sole percentage of the price you paid for the contract?
Monero went up by $20 this month, so it's obvious your returns will be good, but had the price fallen I'm quite sure the contract would turn to shit pretty fast. GM are known for closing unprofitable contracts before their expiration dates. It's a gamble.