I'm not the guy with much knowledge on this stuff, but I must agree the biggest problem is delays. Thinking further, delays make SG addresses more of a temporary, less reliable matter. Thinking even further, getting spam on such a temporary address, well, simply makes you shut it down, eh?
So where is the need of extras (don't know what spf is)
I have no problem in shutting down addresses. I do not use them long term, and never thought they were meant for that. Especially now, with the delays, and with quite some people here having lost really important mails.
Hmmm. I guess I am not that Spam phobic any more. I would never ever use a Spamgourmet address to correspond about a possible employment.