http://xivdb.com/?item/1953/Sarnga
I just assumed the HQ added 1 or 2 base damage, not 4 to get you to 37. In that case, yeah it's closer; worse than Relic / Allagan as you said but comparable and possibly superior to anything else. Still, you need 9 saps for Sargna; I would just go for the relic and save your philos / money.
And you can quantify the impact of crit+ on average WS damage, but as Dan mentions, I have no idea how to quantify the secondary impact of the increased BL procs.