Got to say that the HD500x is a brilliant unit, and you can get some great sounds out of it, used one for many years before moving on to the Pod Go.
The positives are that you can get some great sounds out of it, loads of options, good effects, loads of connectivity options.
The negatives are that you have to buy the HD Bass pack, which gives really only gives you two amp models (and two variations of the SVT), and two cabs. The effects are guitar specific, so for a decent drive sound, you need to create a parallel path, one clean, one dirty. It's not small, and compared to the HX model set, it does sound dated.
Amp modelling is good to have, something like the HX Stomp or Stomp XL might be a good option if you use loads of effects. If you're after a "core" sound and up to 3 effects, then think about a Pod Go.
I do think that you'd definitely need to reconsider the HX FX if you like your amp setup.