Sin's write up is good; I'd add two things. First, the Volvo E-code high beam lenses are beyond belief. Like you, I drive where there are deer, and now I can see them way off in the woods with these things - and my high beam lamps are the *stock* halogens, nothing special. Second, Vision Plus claims 50% better than stock halogen, and I feel like I got something like that....once the E-codes were on. The light that DOT lenses disperse as a fuzzy glow is mostly directed by E-code toward the road, but obviously there's some residual light angled up for overhead signs which I have no trouble seeing.

Whether you buy V+ or HID, the E-codes are mandatory to get the efficiency you're looking for. Check http://www.autolamps-online.com to see if Vision Plus is even available in the lamps required by the 850.