I paddled for a year without a rudder... and a year with a rudder... on a wilderness tarpon 160...
Get the rudder! In calm conditions, the rudder is a mild aid... But in the wind and against currents, the rudder really works well!
Note; serious kayakers recommend no rudder at first (it forces you to learn paddling!) and then adding a rudder as it adds efficiency for distance...
Extra note: In certain conditions a rudder becomes a crutch, or a false promise... coming in thru surf, the rudder does not work until too late, same with going down a river... A rudder needs water running against it to work... When a wave picks you up and you start moving down the wave... you and the water are moving at close to the same speed... The rudder is useless! ( I found this out the hard way!) After some practice, I always went rudder up and hit the brakes with the paddle which is not fun, but a lot safer on me and equipment!
Also, I paddled in Black Canyon, and noticed against the current, the rudder was amazing... down current the rudder was so so at best.
The beauty of a rudder is... you can leave it up!
Good luck!
Cowboybill