Unless I misunderstood that means in the "best" case, you pay roughly half the price per GH for something delivered >3 months later.
The network is currently more than doubling each month, three months could mean 8x lower revenue per GH. Sure that will stop at some point, but not likely in February.
"if you are in a hole, dig deeper."
Also note their ToS. For instance, for batch 2:
Batch 2. All of the 550 Baby Jet units from Hashfast’s second production batch are guaranteed for delivery by February 28, 2014
So if they only ship it by february 28, MPP adds at least 3 months, you would get your extra mining gear no sooner than June 2014 to compensate for your "november" order.
That is a long ways out. They got themselves covered by having you pay a lot up front then and you getting little in return later for all that extra hashrate which doesn't come till much later.