Last night, it worked out for her to do so. We had two strong healers and were a bit low on DPS, so I respecced back to feral and we invited her along to heal.
She did well for a level 68. She contributed about 20% of the healing according to Recount, about 17% according to WWS. (WWS says that our well-geared priest did only 23% of the healing, so she's not far behind there.) Not yet enough to heal with just one partner healer, perhaps, but very solid for someone of her gear.
And she made out very well on loot. She got both the Bracers of the White Stag and the Shard of the Virtuous (plus the off-spec Band of the Everliving)--now she just needs to hit level 70 so that she can use them.