Hey James
I got my Kemper now for a year or so... and every now and then I get the feeling that I bought the wrong unit.. On it´s own the Kemper sounds nicely and all but I cant really handle this sound in a mix.. in double tracking guitars it does not sound anything strong idk xD (lack of skills i guess :P). I am more into djenty death metal and tried TONS AND TONS of profiles, refined them and so on ... but I never really got the tone I could really say about: "f*ck yeah!!"
Here´s an example: https://soundcloud.com/conrad-m-ckel/fallen (just a demo) I feel like it´s too whimpy ...
I'll have a bit of a listen soon (soundcloud is broken for me at the moment), but without hearing it as a general rule, if it sounds whimpy it's probably in order:
1. Your playing (more accuracy/attitude will result in punchier sounds)
2. Your guitar (pickups/tone settings)
3. Amp sound or settings (Kemper)
4. Mix/production
I really doubt that the Axe will do a better job (not a Kemper v Axe thing), because they're both good units and both are used by big acts. It'd suck to pay the extra money to get the Axe only to find the problem still exists.
If you're still bummed, get in touch with me and I'll give you a basic mix of the stems you provide just to rule it out.