100% agree. I was in constant contact with Kemper support and Hans tends to answer very quickly. Just keep in mind that Kemper support is for the Kemper and not IR's. Meaning if they were created correctly, length, etc. In the end I gave up and went back to using Kemper cabs. And you know what? It was the better move as they sound way more dynamic than static IRs. You just have to find ones that suit your needs and tweak them in post. All of this, as usual, is just my opinion.
Funny because on the whole my experience is exactly the opposite. With VERY few exceptions, I pretty much automatically change the cab because I dislike the sound of the cabs that came with the profile. I tend to try and buy/get DI profiles now rather than merged/studio for exactly that fact.
The quality difference has only come to light recently as I was auditioning a bunch of IR's in Logic prior to making a selection to convert and had settled on a few that worked for me and then was surprised by the difference when I loaded them on. thought it was maybe a hickup in the conversion process so did some a/b-ing and found that not to be the case.
I think I have a pack from Tone Junkie TV and a BE100 profile that I've left alone. Everything else (ToneHammer, The Amp Factory, Britt have all had cabs replaced).