I have to say that Spitfire Brass is only my second favourite brass library (it lacks nuance), my favourite being Orchestral Tools Berlin Brass, (though that really needs the mute and additional expansions, which come standard in SSBP).
Being a big fan of Cinematic Studio Strings I was disappointed in Cinematic Studio Brass, which is too fizzy and severely lacking in instruments, though I used my skills to bulk that out a bit.
What percussion are you using? What other main libraries do you have?
Send me an email on chris@sibelius-services.com and I can send you stuff for testing as it's ready.