The reason why I try to never do ADR is due to the actors. I, too, have an experienced sound recordist who has great mics and a nice little studio, but I've found that many actors just can't do ADR well. I've never had a problem with losing dynamics in the voice, but I do have a lot of problems with performance. The less experienced the actor, the worse the performance is.
One thing I do a lot is have the actor do another take right on the spot - bring in the mic nice and close and just do the whole scene again. I've found the replaced dialogue sounds much better because it's done in the exact environment, the actor is more comfortable because it's just doing another take and it's actually pretty to match the audio in post.