Another great thing to come out of Project Conf for me was the connections with people working on some of the same problems that I’ve faced, this is one of those; updating Projects which are checked out is not possible using the same old method that was used with the PSI! (Think about the problem this creates for PDP App Parts!)
Fortunately it is possible thanks to the following undocumented method discovered by Martin Petersen on his blog here:
http://projectserverinsights.blogspot.dk/2014/03/update-project-from-apppart.html
Check it out, and thanks Martin for the solution!