I'm not talking 180 days. MPP kicks in at the end of 90 days, at which point network difficulty is likely to be quadruple what it is when the miner starts mining. MPP hashrate won't come on line until well after 90 days, which means it is worth a very small fraction of the original hashrate. It is just theater. ROI is not being "protected". MPP is nothing more than a miniscule consolation prize.
seems to me 2 conditions need to be satisfied for MPP to be worthwhile:
1. after 3 mo, the difficulty needs to be in a range corresponding to less than the maximum of 5x one's original HR from the point you receive your units. at that point, the MPP can kick in and bring you even to your original investment in the form of the BTC already generated plus additional hashing capacity from the MPP.
2. at that point of #1 the difficulty needs to stabilize or decrease to start returning more than your initial cost in the form of profit.
there's definitely a chance this could happen so it is not necessarily an "roi theater".