I've been a Gmail user since you needed an invite to get in. The basic workflow that I had always used was pretty simple: Message comes into the Inbox, read it, and if necessary, reply to it. Over time, I would tend to have e-mails in which I would want to keep separated and act on them later, so I would just mark those as unread and when I needed to get back to them it was easy to spot.
There is no doubt in my mind that archiving vs. deleting should be won by the archive hands down. I definitely do not believe that deleting e-mails should happen unless they are junk, spam, etc. I like the concept of having a history of e-mails that I can search through and recall at any moment. The dilemma that I have run into is whether or not to use the Inbox as a small portion of e-mails have not been archived yet, or to keep my current flow. So let's break it down:
If I moved to the archived world, I would be able to keep a somewhat cleaner inbox and a more true representation of Read vs. Unread. However, this would require the Archive action for every message that I was finished with as opposed to simply reading the message and being done with it. The great thing about using Read/Unread as the actionable/finished queue is that Gmail supports having the "Unread First" inbox so you essentially get a list of all the actionable items on top, maintaining a clean Inbox experience.
This whole debate started when I began using the new iOS app Mailbox. The entire premise of the application is based on the principle that users archive their messages when done with them. Being a user that didn't do that, I found this workflow to be a bit out of my element. The application is probably the best Mail app that I have used, however the convention of archiving e-mails has me at a crossroads. What might even be a larger issue here is the fact that my e-mail experience is fragmented, and it was fragmented prior to using Mailbox. I use Gmail's web interface when on a desktop computer, and the default Mail app on iOS on my phone, and now the Mailbox app instead. This is problematic because I am having to adhere to 2 distinct interfaces / experiences / workflows rather than having a consistent experience across devices.
Taking even one step back from that, is the issue that Apple is leaving much room for third party applications to one-up their default applications in iOS and they are quickly becoming obsolete. Back in 2007, the default Mail and Messaging apps were the best of the best of their kind. But 6 years later and there are just better, more intuitive, more helpful and integrated ways of handling e-mail from your phone. This problem doesn't only exist with email and messaging either, but any application that has use on both mobile and desktop. There needs to be a unifying consistency that is distinct to the device, but still allows the user to have a familiar and simple experience.