Perceived value

> Copyright assignments break that model.

Two thoughts: First, there's nothing in the GPL that requires the company to cede "control". Second, that implies a loophole: a company can only "control" a dual license (with assignment) project as long as they are the "major player".

I'll bet if you hired a bunch of programmers, you could wrest exclusive copyright control from any GPL project. Just add a lot of neat features, post it widely and refuse to assign copyright (do it privately by just ignoring their emails). The users will complain that the "official" version is missing those features. The first few times this happens, the company will re-implement your features. But eventually, they will be unable to keep up because you only have to add features, while they also have to do bugfixes, documentation, etc..

I predict this will sort-of happen with MySQL: The Drizzle fork will become wildly successful. But unfortunately the old MySQL fork will stay valuable for a many years because there are a lot of conservative companies that will want tot stay with the "safe and proven" MySQL fork. (Heck, the fact that MySQL was worth $1B proves my point -- businesses are too used to paying for software.)