This belt is clearly better than the Sha'tari Vindicator's Waistguard.  It has more AC and one more defense.

Sure it doesn't have as much block rating or any block value, but you can easily add either two +8 dodge gems (for a little under 1% dodge) or two +12 stamina gems to make it a 57 stamina belt.  The stamina is probably the better option, and I think it is clearly a better belt with stamina gems socketed on it.