one thing I would like to remind everyone is the longer you stay connected to slush's pool the better the payout
This is wrong. It's refreshing to hear this myth said
in favor of slush's pool this time. But your expected payout is exactly proportional to the amount of time spent mining.
I think the point that was trying to be made was that in 48 hours you might get unlucky and get a poor payout. With slush running at 180GHs that possible unluckiness is going to be exacerbated compared to deepbit. The longer you stay on slush (or any pool), the closer to the average probable payout you will get. (It's also possible that in 48 hours you get lucky, and then the longer you stay in the pool the less the payout).
Deepbit running at 560GHs is going to get you to a more stable payout quicker than slush. But it's going to cost you 3% versus slush's 2%. So, you'll always earn more in the long run on slush than deepbit.
All things being equal, slush has some great features that deepbit doesn't, which is why competition is great. I really like a lot of slush's stats and graphs, and I also like that slush has a self signed SSL cert that I can use when accessing my account.
Downtime always occurs. Amazon EC2 was out for 24 hours recently, and they have gobs of people and resources. It'll happen to deepbit eventually, so it's no reason to jump ship.