That's a good video by Brian Shulz. I remember reading on his blog about the difficulties he encountered while trying to scale the F1, but I never saw that video. Another confounding variable is how kayak manufacturers decide to name their boats. For example, the Chatham 16 debuted to very favorable reviews and created quite a bit of positive buzz for Necky. So they apparently decided to keep naming boats "Chatham" even though the new boats (like the Chatham 17) were not designed to do the same thing as the original. (The Chatham 16 is more of play boat while the 17 is more of a touring boat.) I'm sure one could point to several design features that both boats share, but the form and function of the boats is dissimilar enough that those two boats really should have had separate names, IMO. That said, I'm neither a kayak designer nor a manufacturer nor a retailer, so take my opinion with less than the usual grain of salt.