Couple of comments from me:
Profiles are not created with a guitar in the chain ( some have setting better suited to a type of guitar), it is a profile of the amp, Cab ( assuming its not a direct profile) and mike
All amps respond differently to guitars and thr Kemper is no different.
So will you be restricted to what guitar will sound good? Absolutely not. I play everything from a Gretsch to a charvel, active and passive pickups, blues to metal.
Do you need an amp? Many people like to profile their own amp but I don;t use my amp profiles. I've use a combination of Kempers amp packs ( you get with the Kemper), those of the rig exchange ( over 10,000 to choose from...free) and commercially bought ones. You will find a sound you like...but...
the Axe and Kemper are the same that they can take time to find your sound although many get it striaght out the box...
I've never owned an Axe FX but the pros and cons have seemed to be that the Kemper can sound a bit more natural but the Axe has the edge on effects. This is a really basic summary so someone else might be better placed to comment on that.
Axe FX and Kemper are both excellent devices, I went Kemper for ease of set up ( built in power amp, minimal fiddling required)...
Hope that helps!