To me, 3.x support in trunk is not really workable unless you drop pre-2.6 compatibility. Bytes literals are pretty much required. A possible workaround is to call a factory function that makes an str into a bytes in 3.x (e.g. write B("xyz") everywhere instead of b"xyz"), but that's quite ugly IMO, not to mention suboptimal.
We're getting closer; we're going to drop Python 2.4 as soon as the next release is out. Still not up to 2.6, though.
Incompatibilities are a given when you switch between two different data models. The incompatibilities don't have to be wire-level, but they *will* occur at the higher level anyway.
The thing that worries is me is unnecessary or harmful incompatibilities that are a result of misunderstanding (e.g. the banana thing, which was an unnecessary wire protocol change). Submitting patches would have the benefit of letting someone else help you make these decisions; it's unreasonable to expect you to become an expert on every single API in Twisted.
Without wanting to sound unconstructive, the "right way" (the "byte-sized" approach) does not sound workable. Some 3.x-related patches (not mine) have been lingering for years, although they are trivial. And these patches (mine and the others) are really the tip of iceberg.
There aren't any python 3 patches in the review queue at the moment; do you have any specific tickets in mind? If they're ready to go they should have the "review" keyword set (if they haven't addressed review comments then that is why they aren't merged).
*Assuming* we find a clean solution to the bytes literal problem, I could try to slice all of that into "byte-sized" patches into which I inject version-checking boilerplate, but that would mean a large waste of time and energy: - for me, as I post dozens of small patches and have to follow up on them, and wait for them to be checked in - for you, as you have to review these patches without perhaps even being Python 3 users yourselves, and without Python 3 compatibility being on your priority list
Most of us aren't Windows users either, but we still try to support Windows :)