As someone who has used a Kemper for a decade... Yup, you guys are 100% right.
Here's where it gets "what to do?" for a guy like me. (and confirming this thread)
So I live in an apartment, record a ton of derpy things.
All with samples of drums, cellos, violins, guzhengs... any weird instrument
that hits my ears. No way can I afford to put a orchestra, or even a drummer, in a studio.
I realize my Kemper tone is a little outside the norm, but I can drop it in there
with all those instruments and it mixes easy peasy lippin greasy.
I drop my Synergy, even through IRs in the mix and... bam, it swallows up
the mix. Basically like Billy was saying. I have even matched the Kemper
profile eq, it gets closer to the mix, and sounds more like some tube... But then most
of my mix goes to crap. Even more of a difference with a microphone, though the guitars are

.
So I am stuck with a Kemper for recording because I can't go to real studios ($) to mike
up the Syn and hire guys
And "stuck with" the Synergy for the inspiring playing
I will say I play my Kemper through a real cab and until you get it loud it is fine.
Not even bad by itself at drummer levels. But once you crank up the amp the Syn30 it destroys.