To be honest, having to do a fork was very unpleasant for me, too. I tried coöperating with Steve Simms and submitted updates to him. He accepted some, but my major rewrite of Content.pm he simply threw away without even telling me (when I asked what had happened, he said it was "too big for him"). It was impossible to re-order Content and massively update the POD (as well as substantial code improvements) while providing the changes to him in only bite-sized chunks.
It's not just a few places in the code where "API2" is used. The whole world refers to the library as "PDF::API2", not "PDF::API, version 2". I was concerned that calling it API3 or API4 would mean it would get lost in the shuffle, so to speak — no one would recognize it for what it is.
Otto's API3 has some code changes in it. Someone reported that the bar code routines worked much better than API2's, so evidently something has changed. I'm reluctant to overwrite all his work and lose it (of course, it could be archived off to the side, I suppose).
I'm open to suggestions on all these issues, before v3.xxx gets enough momentum to make it difficult to change course.
Add: By the way, one thing I considered doing was to offer just a "delta" library of my changed routines, leaving it to PDF::API2 users to merge it into their copy of the official PDF::API2 (v2.xxx) in some manner. I decided not to do it this way because most users would probably regard it as too much work to bother with, just to get some module updates. I felt I needed to have a full distribution in one place.