Household vs Marine-Specific Water Filtration Systems

[Punx]

Alrighty, so here's one of many upcoming questions.

I've done a little bit of searching on how I can convert the St.Clair lake water to potable water. Now there's the marine specific applications for upwards of $2000, and then there's the home applications for under $500. I have a 36' Trojan Tri-Cabin, so the home application wouldn't be an issue on my boat. I was just wondering what the main differences in these systems are. The household system I've been looking at is a 5 stage Reverse osmosis system (http://www.home-water-purifiers-and-...osmosis-uv.php). It's only 50gpd, but for $800 I can get 2 of them and it would be more than enough. I searched through the forum and couldn't find any information in terms of comparing both options. I know there are dozens of different kinds of marine and home based systems, but even the best home systems are cheaper than the cheapest marine systems. I'm just at a loss as to what I should be looking at.

Thanks!