I can fully understand your situation and also certainly know that MODxBB is not just a plug-in. Hence, if I wasn't going to work on it, I wouldn't have recommended you to wait for the next version.
I started as planned last weekend and finally managed to fix the bug on the very top of our "most wanted" list. It was quite hard since it never occurred for me, which certainly means that I had no chance to reproduce it. I will post more about the bug and how I managed to fix it tonight.
I will resume working on the next version this weekend and hope to be done before the end of the next week.
The current MODxBB version will not fully work with the latest phpBB and MODx Evo versions. You will need to do some modifications. That is why I suggested to wait for the new version in first place.
p.s. One additional question: Should all other mods to phpbb be installed first, then your MODxBB bridge/integration? Or can I install other mods afterwards?
That normally doesn't matter, because the phpBB installer recognizes custom changes. If you want to go the safest anyway, install the phpBB mods first.