Well, required coins for masternode is 6-7 btc and roi after two years, it's very long time to get back your investment in my opinion.
No:
ROI is instant because you still own your coins (the principle investment).
If you're saying it will take 2 years to double your amount of PIVX and that's too long for you, then whatever isn't too long for you is an inflationary nightmare and, further, will constantly be generating more and more sell pressure making the price extremely difficult to appreciate.
Otherwise you're instantly generating new PIVX while your masternode coins and the new coins you're minting appreciate in value further.