Thanks for the replies all.
Its been a few weeks of experimentation, but Im starting to get some good results. Not full satisfaction with distortion yet, but enough progress to justify that the Kemper is working out.
First thing I did was to purchase some new profiles, TopJimi's Caswell Marshall and Marshall Jubilee packs. The Caswell with my Les Paul is the best digital distortion sound I've ever had. The Jubilee I use purely for the cleans so far, as I love the Marshall clean tone and this is hitting the spot.
I also did some research as to what EQ to use and downloaded a trial of FabFilter Pro Q 2 EQ. I've been using Nomad Factory plugins for over 10 years now, and its time to explore other plugins.
Also, I'm using the Kempers reverb and delay a lot more.
The results of the above have pretty much opened up the Kemper as a recording tool. Problems I had with my old POD HD is that I had no idea where to go with it, whereas with the Kemper I see directions and possibilities if that makes sense.
Still much to work out, but I'm happy to say that for the first time in my 12 years of home recording I'm starting to feel like Im no longer restricted by my gear. Almost afraid to say that, as I've tried everything that I could minus miking a stack, which is impossible where I live.
Recording at SPDIF 88.2, cant see any great advantage to it. Just habit really, my PC is effortlessly handling 8 tracks.
Next problem is recording bass guitar, I'm getting better results with Amplitube Ampeg so am continuing to use that. I feel the Kemper has a lot to offer when recording bass guitar, perhaps its a case of finding the right profile...