I was referring to Kohana in its current state. Maybe you see that it gives you positive results now, but in the long run your code base will suffer from rigidity (hence your comment below on migration).
Not just my opinion, but all the core developers' too, this is why they decided to abandon KO, it has fallen way behind.
You should read up on clean coding, SOLID, etc. and start to migrate away from the framework now.
You'll be better off and your code base will be much more portable this way. You won't find yourself in the situation where it takes effort and investment to migrate or even upgrade to a newer version.
Check out #kohana and #cleancode on IRC if you want to learn this stuff.
I was kind of ironic, when I wrote there's always room for one more I don't see any reason creating a PHP framework today, instead invest your time in contributing to an already existing one.