Mixing a bunch of files from different cab packs can yield strange results.
All files are phase aligned within a certain cab pack, but when you get to producing 17 cab packs and adding mics to the cabinet along the way, phase alignment between the files of different cab packs is nigh impossible.
You can try delaying a file if you are mixing two at a time. If you are mixing more than two, you would have to add them in individually as you phase align for bass. Guitar is much more forgiving I find, since it is not dealing 45 Hz or lower frequency wave forms for the most part.
I do a video on my site where I talk about building virtual guitar cab stacks and the mixes are really compatible. I never tried it with bass other than the Aguilar 8X10 and mix either the Aguilar 1X15 or Sunn 2X15. Using the HypeReal mixes, I never had issues.