HeadCSO, I am a Wolf Eyes Dealer but have both and can explain the differences.
Both have good lamp assemblies, in either choice I would use a Lumens Factory lamp as I consider them one of the best incan lamps.
The Surefire will have better resale and better HA.
The Wolf Eyes has better battery choices and is more durable. In Australia it is considerably cheaper. If you choose a rechargeable option (financially the only choice in Aus, not sure about the UK) the Sniper takes an 18650 with most having a capacity of say 2200mah. A 17670 fits in the 6P with say approximately 1400mah, 2/3rds the capacity. If you are using this light with LEDs either will be ok, but you specifically said incan so even with 50% incan use you can see the advantage.
A quick word on Hard Anodizing, which I have previously privately shared with some here. I predominantly sell to police, military, security, hunters and other users. All of these people are proud of their front line status and the fact that they are not pencil pushers. None of them have ever asked if the lights are hard anodized. I have seen a number of used lights and most are proud of the "battle scars" their tools wear, it shows they use their tools in the front line and are not pencil pushers. You have probably read that your self here, how many LEO's start a post 'my 20 yr old scratched, dented but trusty Maglite'? I well understand if you are a collector that HA is preferable, which is slightly different to someone using the tool.
You didn't state your use but my suggestion is if you are a collector buy the Surefire as it has HA, good resale and everyone should have at least one Surefire in their collection, the 6P in particular a light which spawned a whole category. If you are a user I would suggest the Sniper as you have lower initial cost, lower running cost and better runtime when you are using it. it is also more durable.
Hopefully that was relatively unbiased and some help, here is a photo of both: