I've gone down this route as well. I can plug into my amps, mic the cabinets and get a great tone. However, I record a lot at night, and the "noise" I make creates issues. I needed a silent recording solution. Here are all of the things I tried:
- Plug direct into recording interface; use amp sims
- Plug into passive DI, XLR to recording interface; use amp sims
- Plug into Line 6 HD500X rackmount, then go into recording interface. I've experimented a good deal with this rig using the HD500X amp sims and cabinet sims together, just the amps sims (using separate cabinet sims in the DAW), using just the effects, etc.
- Plug into my amp, amp into load box, load box out to recording interface.
The last solution is, to me, the best. I have been most pleased with the results of using my amp and different cabinet simulations. I've found that the amp sims I've used (Amplitube and HD500X) are quite good, but not as good as just plugging into my amp (Mesa Boogie 5:25 head).
To my ear, the guitar into the recording interface via DI lacked that last 10% of realism. It's a 90% solution that is relatively inexpensive, but (to my ear) always slightly disappointing.
You can get good sounding recordings with amp sims, and they're only getting better. I've never used a Kemper, but the recordings I've heard with Kempers sound great!
For me, I get the most satisfaction out of using my amps and then running through a load box. I've tried the Suhr Reactive Load Box and the UAD OX. The Suhr reactive load is a great load box. That's all it does. You'll need some type of cabinet simulation solution to go with the Suhr. It's a great device in that it does one thing, and it does it really well.
The UAD OX is THE solution for silent recording for me. It sounds AMAZING. I have one small caveat in that I'm having some issues with the device dropping oiff my home network. It needs to be WIFI connected to use the software. However, the device sounds incredible. It's not an inexpensive solution, but it sounds tremendous.
I think my overall suggestion is that using amp sims will have you chasing tone for a while. The technology is already very, very good and it's only getting better. However, if you have an amp (or amps) that you already know and have "that" sound, you're really better off keeping that amp as part of your signal chain.
Just my 2 cents.