Late this summer I could feel a roughness in my left knee while walking -- though not while riding the bike. I'm hoping (probably vainly) that adding two extra gear teeth on the low end will make climbing slightly easier, and save my aging knees.
A quick initial ride to the top of Perry Hill in the late afternoon gloom on Sunday seemed to confirm that the bike climbed a little easier and that it was possible to carry more rpms instead of painfully grinding up the steep sections... but these impressions may have been largely psychosomatic.
If my situation allows, I may build up a new bike over the winter. My Redline proved to be a great purchase (only only $900 slightly used -- less than a fancy wheelset!) and has carried me through many misadventures on local trails, but it is also -- as is to be expected -- a bike with some limitations.
The questions I need to decide, are how much suspension do I need/want, and what gearing to use? Some suspension is probably attractive, but I feel no desire to ride with a triple front crank... perhaps some version of a 2x9 drivetrain.