Yesterday had an excellent support session with the guys from Visual Web Gui. Some strange issue's were identified that are actually 6.3 bugs which have been fixed in 6.4 and now cause a different behaviour. With some minimal code changes we were able to resolve them, i will check the rest of the code for these issue's today.
We only have 3 must haves left, i just saw in the issue tracker that one of it is already fixed. There are also 3 want to have and 4 nice to have bugs.
So the 6.4 version looks really promising. Looking forward to next beta version to retest again.