Tsunami vs Dragon
First of all, sorry for the late response. I have been away for quite a while.
Now for your question, I’d say personal experience. I have used both Tsunami and Dragon and have found Dragon to be far more comfortable (overall). My build is also one of the reasons affecting the preference, but my friends (on my recommendation) switched to Dragon and they have a similar opinion as well. I know the sample size isn’t much but I believe there won’t be a lot of problem getting similar performance from Dragon. The cost is another factor as well.
not apples to apples?
I think JohnB may be talking about a different Tsunami kayak. He appears to be located in Australia, and maybe they have a kayak there under the Tsunami brand that is different than the Wilderness Systems Tsunami the OP posted about.
Length
If you have a bunch of boats the long ones seem great. In many situations the perform much better. The problem is in some situations they just don’t work well at all. Storage, transport, and paddling tight fits. They are also more efficient if you keep them up to speed. What kind of efficiency will you get if you don’t maintain speed? I have also found those corrective strokes to be more tiresome in a long boat.
I’m mostly near narrow rivers and small lakes though.
Mix-up?
Possibly. There might have been a mix-up of regional names for Tsunami and Dragon kayaks. And yes, I’m located in Australia.
Another brand
The Venture line of kayaks (a less costly brand made by high end maker P & H) includes some skegged models. They are made in England, very nice quality and features for the price. They cost about the same as the Wilderness Systems comparable models but I think the Ventures perform a little better. I’ve had one of their 15 foot Easky LV’s for years and find it very versatile and fun to paddle in all conditions.
If you are a larger guy their Jura or Capella models in MV (medium volume) or HV (high volume) would fit you. they also have the Islay 14 which is comparable to the Tsunami 14 (and has a rudder) but a little more playful to paddle. Not knowing where you are located I could not suggest a dealer but you might be able to find one near you via their website.
http://www.venturekayaks.com/performanceSea.php
Personally I don’t like rudders that much and have never felt my Venture Easky needed one, though it has the option to add one.