I've got an Ultrafire 501 and 502.
Maybe it's just the torches I have but the 501 is finished much nicer than the 502.
I have 2 Ultra fire XM-L drop ins on the way.
I'll try them out with both smooth and textured reflectors as well as flat and aspheric lenses when they get here.
I also ordered some coated lenses that are supposed to increase lumens out the front by around 7% over standard glass. They are cheap and I doubt I'll be able to see the difference but every little bit helps.
http://www.kaidomain.com/ProductDetails.aspx?ProductId=1766
I reckon for the price you won't beat this setup and my modded 501 already blows people away by how much light it puts out. I can easily spotlight rabbits out to 150m with a decent scope on the rifle.
I hope the XM-L throws a bit of light as I'm planning to mount it on a 45colt lever action for night time walk around hog busting !
I have around 8 torches now and I'm always looking for more. Thinking about trying a few of the HID jobbies but they are not something you can mount on your rifle and walk around with.
Moph,
I have the exact same setup as you. Very easy to shoot out to 150m with a decent scope. Most of my mates are amazed at how far it throws the spot out there. Very impressive setup for a few dollars and 15 mins or mucking around. I painted the reflector in matt black epoxy and it removed a fair amount of the artifacts but not all.