I have the SB-400, which should be good enough, its not a terrible large hall, 60-70 people at the wedding total.

Despite seeing very very very few bad responses about KEH (or other reputable used photo equipment dealer), I still have trouble buying used...I see the logic, I see the good reviews, but my finger just wont press the check out button...

Lenses are like the anvils of the photographic world; if there's anything wrong with them, it's easy to see. I've had a lot of luck buyign used from both KEH and eBay, and never hesitate to do try again. If you don't like what you end up with, you can always return it for a full refund.

You're SB-400 doesn't zoom, and only goes as wide as 18mm, so watch out for vignetting if you go wider.