I have been working with a Sabine Navigator 3600 - 3 in, six out, any combo.I really like this box - very flexible - software is pretty intuitive.
If you consider one, get the ethernet option. It's $100 more, but if you need a USB-to-RS232/DB9 converter the price difference is negligable. Wish I'd been smarter about that when ordering.
Even more betterer (sic) is that you can download the software and play with it in "design" mode before you buy the unit so you can see if it looks like something you'd like to use.