AutoDMG and Casper Imaging serve two different purposes. AutoDMG will create a system image from an OS X installer, while Casper Imaging restores a system image to a machine. It really wouldn't make much sense to try and replace one with the other.
Why are you no longer able to use Casper Imaging, and what are you trying to accomplish?
While I can understand that Casper Imaging doesn't fit everyone's needs (we still use DeployStudio over Casper Imaging here) I'm also wondering what the exact situation is. Its possible some of the things you're looking to do can also be accomplished in CI without too much effort.
As for FEU/FUT, yes, these would really only work in a Casper workflow, which, when talking about imaging itself, would mean using Casper Imaging. Nothing else will actually understand what to do with these packages. They are considered proprietary to Casper Suite in a sense.
If moving off of CI is really going to be a necessity, I'd recommend splitting up your packages to have one install the software only with a pkg format, and keep separate "settings" DMGs that you can push via a policy later to the Mac. If you use something like the enrollment trigger for these, they should install fairly quickly after the Mac is enrolled into Casper and set up. In fact, splitting settings out from the software install is recommended and considered "best practice" by JAMF, since it allows you to easily swap in newer versions of the software without needing to repackage up the settings to ride along with them. This setup would allow you to install your software (with pkgs) in another imaging workflow, but install the settings still with FEU/FUT options via Casper.
Outside of all the above, have you considered moving away from FEU/FUT altogether and using Configuration Profiles? Although DMGs + FEU/FUT still works, I personally consider pushing plist files in packages to be a bit old school, when there are more valid ways of settings these with config profiles. Its even possible, using 3rd party products, to create config profiles that apply in a "once" setting, so it mimics using something like a pushed plist file. Just something else to consider.
@mm2270 "Its even possible, using 3rd party products, to create config profiles that apply in a "once" setting, so it mimics using something like a pushed plist file."
Where is this magical utility? If it's "mcxToProfile," I've read from some users on here that it's not 100% effective. That's the main reason I also don't use Configuration Profiles much. I only use them for computer defaults, but nothing at the user level.