I've been using mostly IEMs for about 10 years now and the past 2 years have absolutely been the best. We're lucky to have a dedicated sound man who is a retired engineer. He's not a musician but knows frequencies and how to get a great FOH sound. He bought the Allen & Heath Qu-pac system with extra ports. It's awesome. We control our own monitors with a phone app. He also built snakes for me, the drummer, and lead guitarist. Nice setup. I think our drummer uses 8 channels including a click.
We did have issues on the first three or four gigs with the wifi system due to conflicts with other close wifi routers, but he got it worked out. Not sure what he did but if anyone wants to know I will ask him.
We also run in stereo and our IEMs are also in stereo. Love it!
Both of our guitar players still use mic'd amps. We will never get them to using amp simulators, mostly because they can't figure them out to get good tones. I guess they also need to "feel" the amps. Bass player is all direct.
The one gripe I have with all IEMs is that people dancing close to the stage get very little vocals and keys because there's no presence of them on the stage (no wedge montitors). I keep telling them we need to at least have some side-fills to get a little vocal presence.