On the other hand, turning something you love into your full-time job can oftentimes diminish your enjoyment of it. I've been a full-time perl programmer for nearly 10 years, and while I still enjoy it to a certain extent, when I get home at night I'm so sick of looking at perl code that I rarely spend any time just messing around with it anymore.

The important difference might be what kind of tasks the job will entail. If you're working on a few core products there's much more chance of it getting routine. If it's a job where you're facing new challenges with relative frequency, that can make all the difference.