I had also an unpleassant start when switching to in ear. I tried following the hint of a band mate, he said "it sounds different because you really hear how it sounds"...;-)
It was shortly after the morphing feature was introduced, so I reworked my Rigs to sound good via IEM. Also I moved to morphing as my "lead sound generator".
I use 15 Rigs in performance mode for all my bands and it took me about 3 hours to set up copies to the new method, none of the rigs has a lead boost more that 3db.
I had no complains on rehearsals and after the first gig the Mixer Guy said that my sound improved and that he almost had no job to level my guitar signal during the gig - so I heard how it sounds...
Long story short; I also recommed to work on more than just level. Morphing does the trick to add little more effects, change EQ and to increase volume a little bit and to switch with a press of one button (I should mention that I use the Kemper Remote...). IMHO thats better than trying to catch a signal via compressor or limiter.