erm, no? Indom, Lustrate, excog, and every off gcd arent influenced by either healing boost or healing debuff, regardless of who got it. That's pretty much why a lustrate on a WAR with defiance will do the same on a PLD. (unless that's been changed, but i dont think so).
Fey illumination will work exactly the same as largesse, exept the other healer will benefit from it.