WoW! And I mean WOW !! Just a follow up if anyone is interested. Amazing.
OK. Just like Jothay said. It does take set bonus into consideration. Check this out:
My current dps score with 2 pcs Runetotem / 2 pieces Lasherweave: 9689.3
I change 1 piece out. Upgrading the individual piece, but loosing the Runetotem 2 pc bonus: 9612 (77 pt drop)
I change 2 pieces together (replacing current 2 set bonuses, for a 4 pc bonus) and Bam! : 10,365
Hope this is helpful.