Well I still can't quite pin it down. The dps I get from a vamp seems to vary between 17 to 34 depending greatly on my group setup. Extra proc buffs I'm sure make the most difference. However, extra procs makes spell crit worth more so it evens out as well.
I did snip this from the coercers forum (
http://www.eq2flames.com/coercers/23...nalysis.html):
Or, from a Spell Critical Chance perspective:
1% Spell Critical Chance = 17 dps from Spell Procs
If for sake of discussion we assume this to be true (op will tell you that the formula is still not the be all end all) then 2% crit>vamp handle under any circumstances.