I've been using an HP9800 for the last 3 years. For halftones, depending on the job, I either output them as bitmap halftones from grayscale seps out of Photoshop, or run the job through Ghostscript/Ghostview.
An alternative to halftones that I've been fiddling with is to use dithered diffusion halftones out of Photoshop, which is like what you do with index separations. If I'm printing through a 305 mesh, I change the resolution of my grayscale sep to 200dpi, then so the mode/bitmap/output 200/diffusion dither routine and print my films. The only downside is in open areas you can sometimes get a bit of a stippled look, but if you match the dpi to the mesh count, you won't get moire. A 230 mesh, I'll output the file at 170 dpi, and for a 195 I'll use 150. That's as low as I'll go. I tried a 200dpi film on a 195 mesh and got bad moire.