I switched to mutt after finding myself in the same boat with most GUI clients. After writing a few save-hooks and macros (the hard part), I can check and process all of my accounts in a minute or two, even on a slow connection (great for vacations). Since I version control my ~/.mutt directory, it's easy to deploy on multiple machines. If I don't have access to mutt, my phone or webmail serves as an adequate backup.
