The catch is, at the end of the 5 years, they keep the machines
Long before 5 years the machines will be worthless. Even regular computers are close to worthless after 5 years and they aren't going up the ASIC R&D curve the way bitcoin miners are.
The 5 year contract is like buying a mining rig yourself and use it till it becomes useless. It makes a greater appeal than the 1 year term which pulls you off any potential returns you might get in the second/third year depending on your contract initial mining power and its competitiveness at that time.
I'm currently on a low-end contract with cloudhashing and if I'm lucky I'll get my bitcoins back in around 9 months but I need at least 2 difficulty changes to be 5% or lower. I paid $1000 for 85 GHs for 1 year contract with them but then 2 days ago I discovered pbmining which could be a scam(certainly not a ponzi scheme) or not but surely has a decent price for 1 GH so decided to risk $250 to buy 80 Ghs from them, thats about 4 times lower than cloudhashing for only 5Ghs difference and will only need around 6 months even with difficulty change at current rate of 15-20% to get my bitcoins back. Whether the btc price will remain the same by then its a risk even the btc traders take everyday.
My advice would be to make your own calculations for any potential investment and take the risk only with money you're prepared to lose as every business has its risks, even investment banks(eg Lehman Brothers) go bankrupt so nothing is safe, therefore only invest what you can afford to lose.