Hey everybody, this is Pat, the developer of Wide Email.
I've bought all the other apps as well just to know what my competition is, and as far as I can tell, none of them have the ability to save drafts. If you quit the apps and reopen them later, your text will still be there, but you have to finish that email before you can start another one. Wide Email lets you save an email as a draft, start a fresh email and send it, then go back later to finish the first email. You can save an unlimited number of drafts.
A draft is saved automatically if you're interrupted while in the middle of typing an email ... for example, if you press the home button.
Wide Email also auto-saves every email you send from it. A "Sent Drafts" folder will appear in the drafts list, and you can see, resend, edit, and re-save any of these sent drafts. Mostly this is meant to protect you in case something goes wrong with sending the text from Mail .. your writing is never lost. But it can also serve as templates for quickly writing future emails.
Hope that helps. Here's the app store link for Wide Email, just fyi:
http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=289274499&mt=8
Cheers,
pat