I actually like the extra xp that I get with the overhit with ARcana. The only problem is if you get attacked by another player, it is a bit too slow to protect yourself.
However as I've said, the extra xp for the overhit is very worth it to me.
Arcana more than fine for PvE. Only time to use DC for PvE is when:
- You are CDLing.
- Mobs have Linked Agro (Group Mobs, think MOS Angel groups)
- You are XPing in a Clan War and are XPing in a risky Area (Like MOS or IoP) and can be expective PvP at any time
If you aren't CDLing, killing Linked/Group Mobs, or in a Clan War, you can use Arcana for pretty much anything. The extra XP from overhit that Sovrath is takling about will make up for much of the cast speed difference. Also, if you save shots (3 shots instead of 4, etc.) on mobs it will also make the XP even out moreso.
I actually prefer Arcana for pve and pvp both. The added power is nice, stun resist + interruption resist make up for the slower attack speed imo. Nothing worse than chain stun + interrupt in pvp.