So far I've not had issues with the DS4.5 yet.I loaded a scene saved in DS3A in DS4.5 with no issue.I lost all of my previous DS4 .dsa files in a computer crash so I can't say anything bout DS4.Did you read the release thread in the Daz forums yet? There's info there that may be of help also. That's located here http://www.daz3d.com/forums/viewthread/5343/  but I'm sure others here will pop in also with comments. I think they said some of the third party shaders may need updated but I'd read the release notes to be sure.

Guardian_Angel_671
Daz Studio Coordinator
May the hands of fate be kind to you and yours. :)
guardian_angel_671@renderosity.com