Well - I rather like SE215s. I'm a bass player and sing - we're a Beach Boy tribute (or were as post covid, we're hanging up the shirts) and our band converter to IEMs in around 2015 - X32, later M32 with P16 mixers and ALL of us, including the drummer have them quieter than we had the wedges. I've got expanding foam earpieces on two pairs, and custom ear moulds on the other two. I bought a pair of 400 series Shures and hated them. Better bass, and louder with the dual transducers, but the 215's actually work better. The others are too strange at the bottom end - they're too bassy, so make the notes I'm playing less distinct. The brightness of the 215's enhances the harmonics. One problem IEMs did give me was that I play a 5 string and at first, I played one song that is very much low end - a semitone away from where I should. As we sing pretty well through every song - you cannot look down at your fingers, so starting on Eb instead of E I could not hear on the 415s. On the 215s I can hear the low notes properly.
As we now all have our own mixes we all get better, not worse monitors. There IS an adjustment to be made. Some things you used to do, you can't - like if you accidentally got a rotten wedge mix, you can sort of hear the guys wedge next door and 'tune out' your own. You can't do this on IEMs, so we could not rely on the sound guys mix. If suddenly the keys volume went down, you are totally stuck. We had a reliable sound guy and we standardised on the channel gains between gigs. The differences would be small and would be made up FOH by the channel faders - NOT gain tweaks, which are a killer on IEMs. We eventually had an X32 rack on stage, so gains could again be tweaked FOH without our rack changing it's gain settings. It took me three or four gigs, the keyboard guy took longer, the guitarist a bit less.The drummer had been using wired IEMs via a normal send for ages so was already acclimatised.
Moulds are the way forward though - once you have them you don't want to go back, although my first set were badly done. When I opened my mouth to sing, my ears changed shape inside and they leaked. Second mould was done with my mouth open while the alginate set - these are perfect and I had a spare set made. They work really well with the 215s.
We always put out an audience mic - it comes up as a channel on the P16s but it is a bit of a mess when mixed in - the biggest killer is when the guitarist shouts in my ear mid song - "skip the next one", and you can't hear him. That's the one thing that doesn't work. I'm pretty good at lipreading now. The other thing you need to do is speak into the mics between songs - if you say something, everyone needs to hear it - BUT - in my mix, I have the keys vocal, the drum vocal and no guitar vocal because his harmonies are often similar to mine and his put me off. I need the keys vocal, and a bit of the drum vocal, but I also don't have any guitar, mainly because even with moulds, his amp is close enough.
It messes up totally when you do festivals with no soundcheck and a monitor guy who doesn't know the difference between bass and guitar. Too often I had to pop my moulds out because relying on them was dire. Our solution was pretty simple - we'd prewire the X32 in the stage rack with cables with XLR Y splitters - so the fast changeover would be easy. we'd each plug our split on the end of the cable into our vocal mics (4) and the drum overhead, bass DI, Keys DI and the guitar cab mic - that's 8 sources. The festival people get their feed as usual, and so does out X32 feeding the P16s. Works like a dream and gives consistency.
I now hate playing without my ears. Wedges have totally gone and at my age, it's better for my hearing. It's really nice being able to have quieter monitoring and at lower levels you sing better!
