I assume you're asking about EWQLSO Gold (released years ago), not Hollywood Brass Gold, which is new and much more expensive (and which I don't own).
A few differences:
- KH Concert Brass 2 was recorded relatively dry with close mics. Gold, on the other hand, has the reverb "burned in," i.e. the actual ambience from the concert hall was sampled and is triggered on release. It sounds great, but it's the only sound you can really get. If you like a nice big concert hall sound, perfect. But if you want something else, then you don't want to use Gold. Minimal to no flexibility in ambience.
- KHCB has sampled/modeled interval transitions during legato playing (a la VSL, etc). Gold doesn't; it has a minimal approximation of this using a portamento script, but it's not all that convincing and can't really be effectively used to get that distinctive connected sound in a sustained exposed passage.
- KH has divisi (if your full horn section suddenly plays a four note chord, you can voice it accurately with two horns per pitch). Gold doesn't.
- I would say the only advantage that Gold could be said to have is that the overall production values of the recording were really stellar, so it has that big John Williams soundtrack mojo right out of the box in terms of its color and ambience.
[EDIT] Another advantage that Gold could be said to have is that it has many more types of articulations actually performed by the players. So what this means is that, for example, swells in Gold are actually played swells, whereas in KH you're modeling the swell yourself with Kontakt AET and a controller. More flexible, but arguably less photorealistic. Given that note considered by itself, Gold will sound more real because it is real. The downside is that your way of working with Gold will therefore be more patchwork because you can be less expressive in real time. Neither of these libraries are VSL, and no one should be under that impression.[EDIT]
- Gold has more instruments, of course, being an orchestral set. But you can't get it for $87 either.
I don't want to say "I'd choose KHCB" outright, because I haven't tried the full product yet and although the french horn demo was excellent, there could be issues with the full product that I'm not yet aware of. With that in mind, IF the full product consistently resembles the demo, then the bottom line is that KHCB is a modern, up-to-the-minute scripted library, with all the flexibility and realism that implies, and Gold just isn't. If flexibility is important to you, then KHCB's ability to pull off realistic legatos, divisi and soloing, plus its dry recording conditions, will more than make up the difference with Gold's out-of-box turnkey sheen.
UPDATE .... kinda sorta. See my updated opinion below...
