For fishing a SOT is far superior to a SIK. It is easier to get to you stuff, easier to get into and out of and less confining. In Texas you can fish year round out of it. Just use your chest waders when its cold.
There are three kayaks you should try for fishing. The Wilderness Systems 140 or 120, Ocean Kayak Prowler 13 or 15 and Heritage Redfisher/Marquesa 14. I would try to stay between 12 and 15 feet in length. Longer kayaks are faster and track better.
If you have proper technique, fly casting is no problem. Since you are sitting lower, you will not be able to get full distance, but on the other hand, the steath of a kayak will get you closer to the fish. I think the 13' to 14' length is the best combination of lenght and agility, although I have a 15 footer due to my size.
You don't ever want a crisis to go to waste... - Rahm Emanuel
Who is John Galt?