From my view it is not possible to compare L6, Axe FX .. with a Kemper. The Kemper is a profiler = you get what YOU profile and the result will be great (4U). If you buy some profiles there are ok, BUT they are not profiled in your environment with your guitar, pu's, amp, your settings and dynamic of your playing.
If "I" play with my L6 HD500 it's sound much better as any profile i have buy. Same when i get strait in my Marshall!
And again a big BUT, when i make my own profiles i can't hear the difference & thats the big PRO 
If you play with more than one Amp or use more Amp's in a studio you can make your profiles and you have all in one device = very good for live, at home or in your studio.
My advice: Make your own profiles with your gear, amp, modeller or software "you like" and you will be very happy with the Kemper - so easy
I hope this help!