Thanks for bringing that up, I had been meaning to make a comment. Generally there is no reason why existing -- and installed -- Godzone FSX scenery wouldn't work in Prepar3d v4. I know that there were some heated debates on forums like Avsim about keeping your v4 'pure', and free from legacy scenery, but really that didn't have much basis in reality. Some of the scenery libraries in v4, for instance, and not one single byte different from the FSX versions.
The problem is getting them installed, as the installers don't recognise v4. If you already have anything installed previously, and want to try it in v4, then the xml method is a great way to try it out, I do that myself. If anyone wants specific details of how, when and why to do this, just ask.
Of course you can also use some sort of migration tool to install anything into Prepar3d.
There can be a few v4 issues with older scenery, but nothing really serious. I must admit I don't think I'd ever tried Timaru in V4, so I just fired it up -- I have a 'GodzoneFreeware' add-on.xml file, so I just added a quick entry pointing to the old Prepar3d v2 version, took about 20 seconds to activate.
A couple of z-fighting issues, which make some objects flicker if they are too close to other objects -- like the terminal doorway. The ground polys are FSX -style, one layer is missing shadows, so you see a transparent shadow only under your plane, and objects on the tarmac. Neither of these are deal-breakers.
There may be a v4 version of Timaru in the near future, as this is my local airport at the moment. The last time I was there, the terminal was being upgraded, but I guess it's finished now. At the end of this year I'll have the use of a friend's car for a month, so I'll take some photos then.
In the meantime, I was very pleased with the way the airport looks in v4, this is one of those sceneries which really benefits from v4's lighting/shadows etc:

I'm aware that Hokitika is overdue, as well, but I'm 100% working on NZCH, so it will just have to wait.