We have made great advances with our F4 development. We have finally resolved all of the sql datatime issues (fingers crossed), as well as a number of other reported issues. You can get a link to the download here: https://github.com/joomlahenk/fabrik/wiki/Tester-Instructions
It is also important that you review https://github.com/joomlahenk/fabrik/wiki/Upgrading-from-fabrik3.10-to-fabrik4 prior to upgrading as there are important prerequisites you will need to deal with prior to an upgrade.
It is also important that you review https://github.com/joomlahenk/fabrik/wiki/Upgrading-from-fabrik3.10-to-fabrik4 prior to upgrading as there are important prerequisites you will need to deal with prior to an upgrade.