re rudders, I have em on most of my SIKs and reckon they are invaluable for controling 'glide' into where i want to cast.
A lot also depends on the tracking ability of the yak you paddle, - without a rudder, many tend to want to turn into the wind all the time (weathercocking) causing the paddler to make a lot more corrective strokes to keep going where he or she wants to. This increases paddler fatigue and reduces enjoyment of paddling.
I would recommend you try the yaks in various conditions before you choose one and if you can afford it, get one with a rudder. they really are worth the added expense. (IMHO)
Mate, speaking personally I wouldn't consider a longer yak without a rudder. While you don't need one on nice days, as soon as the weather becomes adverse or you want to apply sideways pressure on a fish, troll structure ect a rudder is invaluable. It also helps you drift in the manner which you want and adjust your angle whilst at anchor.
On a small kayak, they're not needed. And even on a large one, you may not need it. Having said that, I'll be getting one for my X-Factor because whilst I don't need it, I think it will make things that little bit easier and more pleasurable in windy conditions. Paddling with cross wind is a major pain in the bum.
The adventure has a rudder. The rudder is controlled by hand which is fine if you're peddling, but makes it a bit of a pain when paddling. You have to stop paddling to make make adjustments. I find it easier to lift the rudder when I'm paddling. If you end up with the adventure, there is a problem with the lifting of the rudder (as another member, Booligal will attest) - unsure if hobie have fixed it yet. Mine isn't so bad and I can get around it on the water. There is an aftermarket fix available from Hobie so don't despair. Send me a PM if you decide to go with the adventure and have an issue with the rudder.
I havent owned my kayak for long but the times I have tried it with rudder up have not been as much fun, for trolling close to structure it is invaluable if wind and water are going in different directions to me it is also great, helps when I drift to keep things going in the right direction. I read a lot of information before buying my kayak and I dont think anyone said that no rudder was a good thing.