Considering that there's a few specs who gear/reforge/gem around *not* being scaled down... no.
Example: Disc - Geared around legendary meta and quite low spirit. Legendary meta doesn't proc in PG, so you definitely have to swap it out and reforge/regem everything you have. I wouldn't spend that kind of gold for silly solo content. Also consider that certain classes have ways of dealing with mobs that others don't. Disc doesn't have an interrupt. All we have is AoE fear and psyfiend. That's it. Somewhere around 20 priests in the whole world have the 30wave healing achieve. That's for all healing priests, not just disc.
Edit: All priests on healing.