Jan 10th 2010 4:19PM Yeah, it sounds like they're just evaluating the stats on the item, and not the set bonus. In general set pieces will not be statted as well as an item of the same ilvl -- we pay part of our itemization budget for the set bonus. Thus when deciding which pieces to use for our set we're usually looking for the ones that are the least far behind.
In the case of tier 10, the set bonuses are both very good and are worth a good chunk of stat loss. If you're going for the 4-piece set bonus, the legs are the logical choice to leave out of the set. The only real reason not to go for the 4-piece bonus is if you want to keep the tier 9 2-piece bonus (serpent sting can crit) which is a phenomenal set bonus.