I think it would be better if the upgrades tab had the same layout as the achievments. You could just hold the mouse over it to see what it does but then you wouldnt have to scroll through the long list every time.
Can you make it so you can see the bonus for the set without equipping all of the items (and removing items not included in the set)? It is a pain trying to find what each set does then remembering what set I liked best
 "Idle Necromancer"){kind=icon}
 "AdVenture Capitalist"){kind=icon}
 "StrikeForce Kitty"){kind=icon}
 "Astrox"){kind=icon}