I started to make small side projects in FP, but I still can't port my main project to FP+Lazarus, cuz FP is still isn't fully Delphi2009-compatible. It has taken too much time to migrate to using new powerful features, like generics and anonymous methods, so I just can't degrade back to Delphi 7 era again.
It goes both ways actually. Delphi has something FPC doesn't have, as FPC also has something Delphi doesn't have. For example, I've been wanting Linux support from Delphi since 2007, just to be fulfilled at 2017. It's now too late to convert tens of my web apps already running well on my Linux servers, since 2007. Plus thousands of dollar I have to pay for Delphi. As I've said, nothing is perfect. And our miles may vary.
AFAIK, generics had been available in FPC before Delphi, albeit using different syntax. Anonymous methods has been a topic for long and hot debate in FPC forum and mailing list. It raises up again and again every once a while. Everybody seems to want it but nobody really works on it. Well, that's FPC… it offers something more but lack of something else. But who knows if tomorrow someone finds FPC and starting to work on a feature you need. However, my apps can live well without both of them.
One thing about open source project, especially voluntary-based open source project, and in particular FPC project… you can't just request for something and the developers will just provide it for you right away. No, FPC project doesn't work that way. If you need a feature –or a bug to be fixed– and nobody does it for you, for whatever reasons, then you gotta do it by yourself, or hire someone to do it for you. Unlike Delphi, you have all the FPC's source codes and the right to modify it for your own purpose. That can be good or bad, depends on how you look at it.