I'm looking at Rimowa an Koffer's websites for the Salsa Air (or Salsa/Deluxe)...

A couple of questions:

1. Is the Deluxe worth the extra money over the Air? it's about $150 USD more on comparable sizes... other than the divider which is great, what else justifies the increase and makes it worth while?

2. Is there some luggage limitations with certain airlines or why do they make a 29, 30 and 31 inch luggage? I can get 20, 22... 26 is sort of midsize.. but why have 3 in such closer proximity in size?

And since the weight/storage isn't that significantly different, which one is better to get?

Thanks!!