When I next hire someone, they are going to be in group 1 (if I can afford their salary...)

The group 2 people don't learn or expand their knowledge very much from what they had when you first hired them, whereas a group 1 person is forever pushing their boundaries and bringing this into their work.

In the PHP world, there's no excuse for not being involved with your local user group, even if you don't go to the bigger events like the conferences. You just have to want more than a nine-to-five job.