People most definitely still use older phones. I use my iPhone 3G when I travel overseas because there's an easy unlock available for it (unlike the baseband on my current model). And password manager is one of the things I really want to work across all my devices. Actually, if I can't share 1password database between old and new phones, I'll probably be looking for a different password manager. Having said that, I obviously don't expect it to perform fast on older hardware.