The Procenium is voiced like a traditional ribbon (with top rolloff and mids-forward). So it works on the things you'd use those for--all around studio use: electric and coustic instruments, drums, even vocals. Use it where you'd use an AEA R84 or a Coles 4038.
The C and T I've spent the most time with and really like is the Studio Vocalist, which sort of combines the best of both the ribbon and condenser worlds. Not that it is active or uses 48V like the Royer 122, for instance, but it's voiced to have a rise in the top-end, giving it a prescence and detail for vocals that classic ribbons traditionally lack.
I really like it on male voice (have not tried it yet on female) because it has that creamy ribbony mid-range and an almost U87-ish high-end. And by that I don't mean like a modern "Sizzle-heizer" U87, but a good 1980's one. I can imagine that the Studio Vocalist at its worst could be a tad honkey on some singers or sibilant on some, but I've used it on two soulful male vocalists with an API 512, and it has worked great.
