ONYX Thrive
You should also take a look at ONYX Thrive - One key broadcasts the key permissions across your network.
Then you can load as many copies of Onyx on as many PCs as you need until you run out of permissions - or purchase some more.
For example buy a key that allows, say, 8 rip engines, 6 printers and 2 job editors and you can spread these permissions around as many PCs as you want.
You can then have as many rips as you need in whatever combinations you need and change them around instantly.
In addition you can "print forward" so that some PCs do the ripping and others do the print spooling to spread the load, have mirrored setups so that if one rip / PC goes down you have instant replacements.
To tie it all together you have unlimited "Production Manager" consoles running in any browser on any PC / Mac / iPad which gives you an overview & control of what they are all doing.
As an added extra you get a true Adobe PDF engine in every rip so that PDFs are ripped reliably - but with Thrive you also uniquely get Adobe Normalizer which gives the same reliability on all postscript files - not just PDFs like other rips.
Ans as a bonus if you already have Onyx it will look and operate identically so there's no new learning curve and you can get a free trial from your local dealer.
http://www.onyxgfx.com/products/workflow/onyx-thrive-configuration