We have started down the IEM slippery slope here in the RV park we inhabit for the winter.
Our process is, jam a bunch starting in October-ish, then put together a program/dance for the patrons
in the spring, usually March around St. Patrick's Day.

The one last March was a bit of a train wreck.
We had a brand new, digital, mixing board, which no one was intimately familiar with.
We had 2 "main" speakers by the stage, plus a couple of lusty floor monitors.

That would work in most situations. But in ours, we not only had musicians on the stage,
it wasn't big enough so we had some set up in chairs in front of the stage (it's only about 9" high).
When you have a band of "old people" (park rules, "55 Plus"), some who hear well, some not so well,
some with hearing aids, you can't please everybody using a couple of floor monitors,
no matter how you try to place them.

Hence, we're now trying out IEMs.
Not everyone can (or possibly don't want to) purchase them.
Those of us that want them are trying to get them to work, and hopefully omit the floor monitors.
The compromise is, we have a couple of small "personal" monitors that we can hopefully place
where those without IEMs can get a decent sound.

As I said, we're still in the experimental stage.
We've even considered using a bluetooth monitor signal to those with hearing aids that have that capability. I'll report back on this in the spring when we try it all out,
and try to keep the wheels on the track! lol
LLOYD S