In reply to goldmember:
I own and use a Myo RXP, after seeing the Alpkit Gamma recommended on here I got a few bought for Duke of Edinburgh use. The Gamma is 12.50 quid, the Myo RXP is about 60 quid.
Very impressed with the Gamma, no it isn't as good as my Myo RXP. At a guess I would say it has about 80% of the throw of the RXP both on fresh batteries, which is amazing value for money and they stood the use of duke of edinburgh kids for a year so they can't be that bad. Not had them out in horrendous conditions though so can't comment on rain penetration etc.
The Myo RXP is regulated though, so doesn't drop off power as fast, takes lithium (more powerful/better in cold), rechargeable and normal alkaline batteries.
In short, if you want that edge the more expensive ones have over the Gamma, then get a Myo RXP or the like, if your just after a pretty decent head torch for night use then get the Gamma. Hell if you get the Myo RXP you could just throw the extra money in and get a Gamma as backup!
Hope that helps
Craig.