I had hoped that version 4.4.0 and above would use Qt 5.x. After all, it's been nearly released a year. However, there are some real problems:
– Functionality changes. These can be handled, though.
– Stability issues. In particular on Linux, it appears the port to use XCB has created many bugs with remote displays.
– Lack of support for existing platforms. Qt5 does not support RHEL5/CentOS5 which is the 4th most popular platform after win64/win32/Ubuntu64. This is really inexcusable.
– Failure to even compile on Mac OSX 10.9. Yes I guess it's not really their fault, as Apple have delivered an OS which is deficient in many ways with regards to back compatibility. But the beta was out a while, dear Qt folks…
So the bottom line is that I'm rolling back Linux ports to Qt 4.8 and the same to Mac OSX ports. The Windows Qt5 port I'll keep just to see what the stability/problems are like – so far I have had no reports of bugs. If you see any, let me know!