How big is your tank?
I don't have direct experience with the hood you are referring to, but using MH is a whole new world. These lights can get VERY hot and will need to be maintained well above your water surface (or at least more so than your standard FW hoods). You would be best to ceiling mount them. You can also install a fan over your tank or sump to displace some of the heat, but this would necessitate frequent topping off... Depending on your local and indoor climate, this may or may not be a problem... Just remember that the lack of MH in freshwater is also one of the reasons you don't see water chillers (also not cheap) on this side of the hobby...
That said, MH lights are awesome, and Coralife typically makes good hoods... If you are looking for an adventure and have the cash to blow, I say go for it... As long as you come back and let us know how it goes!
Good luck.
