I'm a developer and have done 2 themes for one of my clients. I'm unable to get the theme switcher to work (for the comments page, it reverts back to default theme) for her. She's a personal (not commercial) blog client, so my b udget isn't huge, but I'm willing to pay for someone to help.
Quick FYI: I'm using Ryan's theme switcher. Also, her files are located at domainname.com/wordpress but we have the blog rerouted through header modifications to domainname.com. I have a feeling this is causing some cookie issues.
Feel free to email reese AT m2webstudios.com.