You would be quite amazed at what those skinny little boats can carry, technically I think they are called surfski's .
If you look into the rules for the 300 mile Watertribe endurance race everglades challenge (EC) at (www.watertribe.org
) you will see that the rules state the this race is totally unsupported and you must be totally self sufficient (no outside help of any kind is allowed), and you are not allowed to add or remove things from your boat, basically if you start out with a scupper cart, you have to complete the race with that same scupper cart. Also you are required to carry cooking and camping supplies (stove, tents, etc) and your own food and water for the trip, (though water can be replenished at the 3 checkpoints "only"). You are also required to launch and portage with no outside assistance. On the Watertribe ultimate 1200 mile race this includes a 40 mile overland portage (i'm not up for that one).
There are 6 different classes of different types of boats (the AI's and TI's would compete in class 4 and 5, or because there are so many entered recently , they actually created a separate class for the Adventure boats (well named).
This race is not for the faint of heart, it is utterly brutal and tests even the best kayakers limits. In classes 1 thru 3 most of the kayaks are professional class sea kayaks and surfski's (most cost way more than a TI) like Krugers, and several other famous brand sea kayaks and surfski's.
The Revolution and most of Hobies Kayak line are what they call recreational kayaks (a totally different world).
There is definitely a relationship between kayak length and speed. I own a Tandem Island and in kayak mode it is Hobies fastest kayak (because it's 18.5 feet long). I'm a pretty strong endurance peddler yet I recently spent a week down in the keys in a cabin next to a family who had a couple Hawaiian proa surfski's, this is the kayak he as ( http://www.kamanucomposites.com/aukahi
). The thing was 24 ft long and weighed around 20 lbs, I consider myself pretty good on my TI but this guy left me in the dust every single day, he was not just a little faster, he was way faster, and talked about many trips he has taken in the hundred plus mile category.
In conclusion, the Revolution, Oasis, and most other of Hobies kayak line are very good recreational kayaks ( the best made). The adventure series boats with their offshore stability and trimaran sailing ability makes them a very suitable for open sea adventures and endurance races, races like the EC challenge (that's why they are so popular in such races), plus I know of no other all around family fun boat as nice as the TI (we call it our SUV). Watertribe has several races in different areas throughout the year in different regions (it's a pretty good group)
The Missouri river 340 would be an excellent race for the Adventure Island and the Tandem Island class boats, but they would need to create a new class for us (allowing sails), currently I don't believe sails are allowed, and my understanding is you can have all the external support you need (we need none of that stuff).
All this just makes me even more impressed with Reeves performance in the Missouri 340 in a recreational kayak, (most impressive). Actually Hobie doesn't even sell the Tandem Island as a Kayak, it only comes available with all the sails and AMA's. We enjoy our TI very much as both a very capable sailboat, and undeniably Hobie's best tandem kayak (that no one can buy LOL).