I've used H322 with heavy (90 gr) bullets in .223 Rem with a 30" barrel. IMO, it's simply has too fast a burn rate for such an application and creates pressures issues well before something like H4895 or Varget. In a .223 Rem with 80.5 gr bullets and a much shorter barrel, I've used H322 with excellent results. I've never tried H322 in any other caliber, although I suspect it could work in a variety of different applications, especially those with relatively light-for-caliber bullets. It's an awesome powder for the right application. In my mind, I tend to think of H322 as being in the same class as Benchmark and IMR 8208 XBR, which are just a bit faster than Varget, although you could easily argue that they could be classified as being at the upper end of powders in the general burn rate range of Varget. Powders in this range excel in the .223 Rem with light to medium weight bullets, PPC, and a number of other smaller cartridges. They can work also very well in a .308 Win with light to med weight bullets (</= ~160 gr).
So the real key is to choose a powder that's optimal for the specific situation. Cartridge, barrel length, bullet weight, and other factors, all have an influence on what powders will work optimally. So there is often quite a bit of overlap between powders that are roughly in the burn rate range of Varget. The choice is often not about velocity. I will almost always take precision over velocity, and with many of the powders in this range you're only talking about differences in velocity for tuned loads of maybe 50-75 fps or so. That is not a huge velocity difference, IMO, and not something for which I would be willing to trade the best precision. There are also pressure and brass life considerations, and sometimes powders that are considered "very fast burning" for a specific application tend to generate higher start pressures and be harder on brass.
In general, a powder that gives you reasonable velocity (i.e. not necessarily the highest velocity) with excellent precision is the best way to go, IMO. If you want more velocity you can always go with a double base powder, accepting that it will potentially be more sensitive to temperature changes. Velocity without good precision isn't of very much use, so a powder that gets you to approximately the same velocity region as other powders in the same burn rate range, but with better accuracy/precision, is what I usually try to look for.