Can you actually see underwater with the MiniQ40? My experiences with one, I couldn't make out objects beyond arm's reach, in semi-murky but typical of Sydney harbour.
Surge is the brightest thing from PT, so if you like UKE stick with them. Their rechargeable range are excellent. Cannon HID also, as Brock mentioned.
I have a UK light cannon and it is great for night diving or straying slightly into caves. It is not as robust as I would like as I do alot of rough entry diving from beaches, slides of cliffs, etc. and I HAVE broken the light. Not a pretty sight when you turn the switch on and don't get the usual warm up flicker.
UK LC100 definately. This guy can withstand good depth without leaking. It is also one of the brightest diving lights you can get for under $200 and is easily portable. And it lasts around 8 hours, with 5 or so hours of really bright light. I use NiMHs in mine, and it works perfectly fine.
This guy's equal to 3-4 Surges. It'll light up the floor quite well, and its color rendition is a hell of a lot better than incandescents.
The nice thing about HIDs is that their high blue spectra content will carry farther in water than incandescents, whose shorter wavelengths lose energy more quickly when submerged. The LC100 is not one light you'd "compare over the counter" (as their own marketing material states)
Frankly, I can't think of any light - waterproof or otherwise - that has the same brightness, runtime, weight, bulb-life and battery flexibility (you can use C-cells or a special rechargeable kit) and price as the LC100. And if you're diving to take pix or videos, this light will more than double up for that duty.
I don't dive but I have seen many of their lights. Check out these dive lights.
If you want a review for these lights do what I do. http://www.google.com/grphp?hl=en Go here it is googles usenet search engine. Use + before words to tell the search engine the word must be in the found text. Enter +nameoflight or +manufacturernumberoflight. You'll get good reviews.