I can highly recommend Harm Smit and Popped Web as an enthusiastic, responsive and highly-knowledgeable developer.
I've worked with many developers over the years and generally work with a local firm. Recently I updated my older v4 CS site to a new version with Unitheme and we worked to get it the way we liked on our dev site but were at a loss to get it live, as upgrading CS Cart and reinstalling UniTheme seemed to remove most local changes.
Harm was most willing to help us transfer to files, and helped to make many great suggestions on making it run well. He knows UniTheme and is actually working on some new themes as well.
Since then he has helped us troubleshoot and fix many small errors. He's extremely responsive and reasonably priced.
Optical Ocean Sales, LLC