One of my bands uses a Behringer X18.
we decided to get IEMs too and lose the backline.
FOH is a pair of Bose L1s, each of which has a pair of B1 subs.
Last gig, we decided to do without backline and go totally IEMs.
I did some homework before the gig and, using X Air Edit, on a laptop, I set up the IEMs.
I paired up aux 1-2 and aux 3-4 to give two stereo mixes as we have two transmitters and six receivers.
Mix one is quite balance between vox and instruments. Mix two is more vocal heavy.
The individual can choose his mix on his belt pack. mix one or mix two.
As the X18 has 6 aux outs, we can add another stereo monitor mix.
It went as well as I'd hoped, in fact some of us came away from the gig thinking, "I'm not as good a singer as I thought I was".
How did I benefit as a bass player ?
Everyone could hear me better, everywhere on stage because my backline wasn't being drowned out by a guitarist, I was in their ears, so was everyone.
I now don't know if I'll ever use my Markbass setup again. Certainly not with this band.