Both are great setups. I think the Dart is really a rebadged Screen machine, and if so they are excellent CTPs and there are lots of techs out there who can service them without having to go through Fuji. Also easier (maybe cheaper?) to get parts when necessary, whereas with the Kodak it's a bit more proprietary. I'm currently running an Achieve 800 with autoloader using Sonora plates and we're happy with it.
I also use Prinergy and it really is the best workflow I've ever used, but in fairness I have not used XMF (though it has a good reputation among its users.) If you spring for Rules-Based Automation (RBA) with Prinergy, it really opens doors with letting you automate all kinds of things, but it is very expensive and it can be complicated to learn in order to get the most value out of it. XMF is probably less expensive up front as well as over the long term based on what I've heard.
See if you can visit a shop that uses Prinergy and one that uses XMF and spend a couple hours with the folks who use it all day. They will tell you what they like and dislike about it. I did that once years ago when shopping workflows and if you can get the salesman out of the room you'll get the straight story from people in the trenches.