Just my opinion FLRick - you are right - I have never tried it. I don't scuba but help out on a boat that people scuba dive from. Lifting the tanks and the gear seems heavy to me but I am aware that anyone is capable of anything they set their mind to.
Over here with my conditions I would consider it very hard to take two tanks on a kayak and dive safely.
But we don't have launch fees and I live by the sea (currently kicking up quite a swell/chop with a nice F6 wind !).
True kayaks are lighter and easier to handle but in my opinion they are better suited for just paddling or for freediving where you have minimal equipment.
Many people either scuba from kayaks or from Zodiacs. I just think that it would be hard to get a kayak that you would be happy paddling for any length of time loaded with tanks and scuba gear. But that is my opinion - I like efficient/fast kayaks and someting like the Fish n Dive is not exactly streamlined. The Scupper or Scrambler would be nice and propbably a good compromise if you intend to tank and kayak.
Perhaps it is a good method when you have to pay for launch fees and only go in summer / paddle short distances (a mile - 10 mins is short).
Unless you have everything very well strapped down or you paddle summer days when flies walk on the water then you will have a few falling out moments - a friend borrowed my kayak to follow her boyfriend who was spearfishing and managed to loose her bikini top - which just goes to show that loosing things in kayaks is an all too common occurence....
So Tahoe Diver to give you my opinion for the original question :
Have a read on paddling.net and ask people what they use for the same set up and conditions. I reckon that there are three basic levels of kayaks (all SOT) - the first is the 'fat mama' - very stable, can carry alot but has a short range unless you have gorilla arms and you might need a mate to help you carry it.
The second is the ones like the Scupper/Scrambler - they will be faster to paddle, slightly less stable but probably a good compromise and the last are the sleek surfski/ocean-designed kayaks. Probably too sleek for using two tanks with but again that is just my opinion.... Good luck with the decision - make sure you try a few - often the folk on paddling.net will let you try one out if you are in their area and I bet there are heaps around your way.
They also have second hand kayaks which if you are in the USA (which you are) are probably a better bet than buying new - you can try it out for a fraction of the new cost and see what suits your needs...
Guess you'll be asking about paddles next...
