there you go:
A personal shopper seems a bit extreme. There are plenty of stores with excellent customer service, I shop at many of them. This was a pretty simple case, however, Unionmade entered in to a contract that they did not fulfill and then jerked me around for weeks. So I will always recommend avoiding them.
I just picked up the medium duffle and it is very large. Larger than a carry-on size limit if filled to capacity. The "large" size would be for well over a week of travel (at least the way I pack).
Also, I think if you filled the large duffle up, it would be way heavier than you would be willing to carry. Although, perhaps you are some sort of muscle man? I've seen pictures of people carrying the large size, but it always looks less than half full.
These guys say the large is for "a month-long trip" http://www.formatmag.com/news/filson-large-duffle-bag/