People on HN/Reddit are pretty biased when it comes to CSS knowledge almost to the point where I really wonder if they've ever worked at a place outside of a startup or a tiny company. If you work at an creative digital agency, chances are the division of labour will mean you won't ever have to touch a line of code. It just makes more sense to divvy up the responsibilities. Plus, during client presentations, most of the designs are mocked up as flats instead of live code.

I'm currently using CS5, but it's largely because of some of the small addition features with smart objects, workflow, and layer styles that annoyed me with CS3. It's one of those things where you have to work with a program for a long time before you notice these small upgrades that really help the day-to-day. I think you're fine with CS3.

The idea that GIMP is more than useful is... debatable. I would say that every notable designer I know in NYC/SF uses Photoshop. Like it or not, it is the industry standard. And while I do sometimes have a love-hate relationship with the program (specifically because I want more stability instead of new features), GIMP is still far behind with regards to it's intuitiveness and penetration.

Now that I've migrated to a startup, I use Photoshop for quick initial concepts before coding scss. Photoshop is pretty solid for making elements or re-using templated elements made from other designers and photo-editing.