It's pretty much a break even scenario from 1300 on forward - you don't actually lose/gain anything from them from a damage inc/outgoing standpoint.
However, stacking expertise into the mid 1300's still provides minor benefits to healing (which is what I do).
I run at 1320 expertise these days, I have one advance resolve 27 armoring (non expertise) I use that drops 50 off of my max already.
Ah, I've been stacking PVE stuff lately since I have access to it. I have 27 armorings in belt and bracers with EWH offhand mods, power crystals in main and off hands as well as BM implants still since alacrity is crap. 1196 expertise or something like that just shy of 1200. Honestly I've accidentally run in 61/63 PVE gear before and didn't even notice. The boost from all the extra stats has been far better than the additional expertise imo as a sorc healer (well hybrid for the time being).