I've found that it entirely depends on the vendor. My HP printers, using the Apple drivers, usually continue to work fine after driver updates. The Konica Minolta's, though, completely fail, and the printer needs to be re-uploaded to the JSS and redeployed to the clients.
Part of this has to do with how Casper Admin uploads printers to the JSS. It seems to me that it creates a custom ppd with the printer information and the printer's ppd from /Library/Printers/PPDs/Contents/Resources/* and uses that PPD to create the printer on the client. IT doesn't contain other support files, though, such as CUPS filters and the like. And I think that's the source of the compatibility problems - this custom ppd, containing version x.y, fails to work with version x.z of the driver software that is installed later, such as the CUPS filters.
If I create printers via script, the compatibility problems are minimized (well, that, and getting rid of the Konica's). That's probably of little comfort to you, though.
