I have a compressor without pressure adjustment. It would probably involve less guesswork on my part if I had it regards to thinning paint. Then again, that's 2 things I'd have to learn! It cannot hurt and offers you more options and control.

I have the Tamiya Spray Work Compressor. So far have painted about a dozen tanks and models with it. And judging from everyone's comments, it paints pretty well as is.