Well, I'm going to go ahead and respond, but hopefully someone more expereienced will pipe in.
3-5Meters isn't much worse than the vis I dive in regularly (3-5meteres roughly is 9-17feet)
I personnally use a $70 UK C-8 Light and enjoy it quite well. One of my buddies uses the UK Light Cannon (HID) and though it works quite nicely at times I think my light outperforms his (mainly in shallow depths were ambient light is at a decent strength) From anything from 30feet on a sunny day with 25foot vis, to 94feet with a total silt out (around 2feet vis) I've used and liked my light.
One thing to think about is that visibility is usually due to algea, or other junk in the water collumn. This "junk" works in much the same way as fog does. Light shinned on it will be blocked and reflected back. Getting a brighter light will just relefect a brighter portion back to you... That being said, the brighter light will also be more noticable for the bit that does penetrate (to other divers) so you are easier to spot by them, but you still cant see any farther than with a dimer light.
Personnaly I can't see spending the money on thoose Niterider lights. For the money you could buy the UK HID light cannon and get HID light, OR spend a little more and buy a canister light (by far the best light I've seen in use was a canister light)
If memory serves the UK C8 I use runs around an 18W bulb for approx 4hours (for reference)
The nightriders do appear nice being hands free, but I personnaly have never had a need for hands free operation of a dive light.
Just my .02 cents and most humble opinion... I'm sure no matter what light you get will do great as long as a few things are met.
1) is it reliable? Will if flood or need repair offten? (sometimes simpler is better)
2) runtime and availability of batteries/chargers If no charging is near by either alkeline or LONG runtime recharagbles are needed, make sure you get a light that can run the time you need it to run with amble reserves.
I guess thats all I can think of at the moment, other things may come to me, or hopefully someone will 'pipe' in and help me out.