It's widely acknowledged that Deepwood sniper is /worse/ than arcane archer for averything other than flavour builds and splashing into rogue mechanics, interestingly, the original PrC that it's based on is very very good, see the active "sniper shot" ability is more or less a passive feat gained at level 2 of Deepwood sniper (if we assume progression of a PrE is 3 or 4 levels of the PrC per level of PrE then a Deepwood sniper I would receive:
Improved critical: Ranged
The current sneak attack range bonus
Hide/move silently +2
+1 to critical multiplier at ALL times.
+10% chance to bypass concealment/incorporealness (so miss chance on wraiths etc is only 40%)
Some form of bonus feat (many of the possible feats are not in DDO, so some other form of bonus might be easier, maybe give the "Sniper Shot" ability that's already in place instead of this)
Safe poison use (as poisons aren't in DDO there's not much point to this, maybe poisons SHOULD be in DDO, the deepwood sniper is essentially a ranged assassin, maybe an imbue arrow ability as with AA but just a few types (maybe the ability to add puncturing to any weapon at the cost of SP?)
+1 enhancement bonus to all shots fired (non-stacking, probably useless as +1 or better items aren't exactly rare in DDO)
I realise that this is probably erring on the side of overpowered rather than underpowered with these bonuses, and I wouldn't suggest all of them be in place, but I think the current "Sniper shot" should lose the +4 to hit and just be considered always on at the very least.
Further, a brief notion on Deepwood sniper II and III:
II:
A further +1 critical multiplier
a further 10 yards to the sneak attack range bonus
Further +1 hide
Further +1 move silently
Take AIM: Either a short term buff (like manyshot) or a reasonably long cooldown activate ability, gain +2 to hit and 2d6 bane damage (except on creatues which cannot be critted)
III:
+1 hide
+1 move silently
Increased critical threat range +1
A further 10% chance to bypass concealment/incorporealness
Take AIM Bonus increased to +4/4d6
Again: I know this takes DWS from very underpowered to pretty **** overpowered, I am not the council of game balancing, I've just always wanted to play a DWS but not wanted to be a total Gimp, though bow of sinew plus Sniper shot sounds pretty sweet.