I dislike mouseover macros for GCD healing, but don't mind them for oGCDs. In fact, I use mouseovers for Benediction, Tetragrammaton, Essential Dignity, as well as Embrace, and have never had a problem with them.

My former WHM co-healer had everything on mouseover. It worked fine most of the time, but every now and then his macros wouldn't trigger due to lag/latency/packet loss and he would miss a GCD, which would result in deaths.

I don't know, I think it's up to everyone's preference but I personally wouldn't risk macroing everything, and I like my GCDs queuing smoothly into one another.