3.4/develop

Fully embraced the composer way of doing things, added requirement of PHP 5.4+, and added some fancy new 5.4 stuff.
I see the motivation for going to 5.4 (and we're looking to go to 5.5 for our internal projects) - however, we also do work for a couple of clients who distribute on to third-parties. Some of their customers are still running 5.2 (on RHEL LTS) and it's taken us a while to get agreement to a 5.3 minimum version support. 

Several of those third-party customers deploy the code we're producing alongside other (semi-unsupported) apps, and are nervous about moving beyond 5.3 because of the potential for issues.

It's not an ideal situation, obviously, and we're pushing as hard as we can to get them to migrate - but at the end of the day we have to meet customer requirements and it would be disappointing to be locked out of using the new and improved Kohana at this point. I'm sure there'll be others in similar situations.

I'd be more comfortable with forcing 5.4 to take advantage of major new features, but perhaps we could find a way to do that but minimise (in the short term at least) the number of places that we switch to using 5.4 syntax treats (like the array initialisers and constructor chaining) to make it easier to maintain some sort of 5.3-compatible fork. If we change every file just for the sake of code style that will be quite tricky.

Bearing in mind we already have a relatively small and fragmented community, seems a shame to leave anyone behind at this point unless we absolutely have to.