My cousins 3 piece use in ears, all hardwired, and that seems to be a good viable option. I haven't tried it myself, granted but personally when it gets too noisy on stage, I have almost a "sensory deprivation" kind of feeling. Hard to describe, but the upshot is that I over concentrate and I'm more inclined to make mistakes.
My current band uses bose column speakers as a pa, which belong to the singer, who also does the mix. This means that it's hit or miss whether I hear myself (he mixes himself 75% above the band) and as the stacks are on stage, it's incredibly loud.
My idea for singing and in ears is for a future idea. Although the wharfedale is a neat little unit