Crossbows As A Main Weapon? (PvE)

Hey guys,

So after having beaten the game several times I'm now looking for builds that just seem cool to me or would make it harder. I'm in the middle of a SL1 playthrough right now and I just started thinking about using a crossbow as a main weapon in my next playthrough. Had some questions though.

First off, does going an elemental route with a crossbow make sense? I keep seeing different information posted on other forums. Some saying they don't do any extra elemental damage and some saying they do, so I'm not sure who to believe. Second, do you guys think a main-weapon crossbow build is even viable?

I'm thinking since crossbows have no stat scaling there's no point in me putting more points into dex or strength then I need to wield the various bows so I could just level up vit and end mainly and be able to fast roll in some heavier armor.

Looking at this as a possible build http://tinyurl.com/98frm9r

Now with a maxed out Fire Avelyn and lightning bolts apparently it'll be doing 422 damage per hit, and since it fires 3 bolts at a time that's over 1200 at a time which seems pretty nice. This is assuming elemental crossbows are viable though. Obviously I'll have the off-hand sword for when I run out of bolts, BSS is just a placeholder, it could be any light sword really.

Anyway, I'd appreciate any input on this idea.

I've summoned a guy doing some SERIOUS damage with the Avelyn.

No way am I good enough (or patient enough but that's besides the point) to do a SL1 playthrough but I'm playing through with a SL20 and the heavy crossbow+10 with heavy bolts has seen me through all the tough spots. I never ever even thought of using a crossbow before in Dks or Des but it's a lot of fun.

I've also heard different things about the elemental upgrade. Hopefully someone knows. I doubt you could use lightning bolts on a fire avelyn though. Or maybe you can but I doubt it deals both types of damage.

Can you deal two types of elemental damage simultaneously with any weapon?

Heavy crossbow +5 lightning with lightning bolt,
Possible dual Xbows with avelyn with same upgrade.
You can also dual bows with fire composite bows and fire bow of Pharis.