If there's a particular item you're looking for, call the store you're thinking of shopping and ask if they have that particular item in stock (and if they have many of the item).

Not all items sold at Tumi outlets are "seconds." The outlet store I like sells not many seconds, but rather almost all first-run items. They do carry quite a bit of last season's or discontinued items, and current lines.
Just as an fyi, the 22" rollaboard is 22" for the bag compartment alone and doesn't take the wheel extention into consideration.
Since the inventory at the Tumi outlet stores is hit or miss, it helps to go into the store with not only a good idea of what one wants, but what features one is willing to compromise (if necessary) in order to get the outlet store pricing. An example of what I found at my favorite Tumi outlet when I was looking for a Gen4 or Gen3 rollaboard is they had the expandable Gen4 rollaboard line (with suiter), but only in the brown color. They had non-expandable/non-suiter Gen4 rollaboards in black. They also had expandable Gen3 rollaboards (with suiters) in black.
This varies and IMO shouldn't be made as a blanket statement (not just above, but similar statements have also been made in other threads). Items can be purchased at outlet stores with a full warranty. I have two pieces purchased at an outlet store and I've talked with not only the outlet store in question, but also Tumi's customer service, about this. I was assured the warranty would be honored (if needed) as the items purchased were not considered "seconds" or otherwise in a condition that would void the warranty (such as the item being sold with a noted defect). It's definitely something to be cautious of, though.