Just thought I would post an update in case anyone ever has rudder/steering problems, and needs another avenue.
TL;DR - it was a knot in the limiter that made the limiter too short for the handle to move the rudder full sweep
Was out sailing on Sunday, and once the wind picked up I lost the ability to steer port, and steering to starboard was very slow). I've always thought the steering from the rear seat (where I always sit) was dismal, but this is the first time I could actually not steer through wind. I decided then that I would completely disassemble and re-install the steering. I am one of a very small number of people that have steering concerns, so I'm sure it wasn't "just how it is".
I ended up doing a lot of poking, prodding, and taking pictures inside the hull of the TI to figure it out and see if there was an obvious problem. I found a cable of possible concern and was able to roll it off the stud on the aft steering handle, leaving it hanging loosely from the string going to the forward steering handle.
This pretty much disabled the ability to steer from the rear (would only steer one direction), but it allowed me to adjust the rudder for the front handle, and found that with just the front attached, the steering worked almost perfectly (no stiffness, rudder had almost an inch of extra sweep). So then I knew it was an issue with the rear...
Next I disconnected the steering line from the rudder, pulled the guide tubes out, and started digging around more (at this point I still didn't fully grasp how all the lines interconnected). Finding no issues with the lines running aft of port quarter I reinstalled the guide tubes and lines, and started tracing every inch I could reach with my fingers. The last thing I checked was a line running directly from the rear handle to the starboard side (later identified as a "limiter"?). I felt a figure eight knot in the middle of the string, and although thinking "how much difference could a little knot on a random string make", I decided to just remove the string and take out the knot...
With an allen key, I removed the yoke from the front handle (inside the hull)
which gave me enough slack to remove the steering line loops from the knob at the rear handle, and was able to pull the knotted string out of the 8" hatch and remove the knot. I put all back together again (3 loops onto the knob at the rear handle, re-install the yoke, reattach the lines to the rudder), this time in a way that ensures they won't slip through the little screws on the rudder, and found that rear steering now works just like the front!
So if anyone ever has issues where their steering doesn't seem to swing fully, check that limiter line; if its guitar-string tight and the rudder is not fully turned, it could be the issue.
I hope this helps someone in the future. The steering was one of the most disappointing things about this boat, and I was getting close to just figuring out a way to install a tiller directly to the rudder. Hopefully I will get a chance to test it out this week...but I'm thinking with an extra inch of rudder sweep each direction, it will be much better.