Many times, I have said that flyer bearings were not very important.
Well, I put high-quality ball bearings on the Alden Amos #1 flier and raised its top speed with the 5 tpi whorl/bobbin from ~2,200 to 2,500 rpm. With the fines whorl/bobbin, it peaks at ~3,800 rpm However, the new bearings with their heavy duty maidens, some changes in angles, and architecture allow the wheel to run much more quietly, despite going ~14% faster. I did not change the ratio, I just captured energy that was going to friction.
It is not a lot more speed. A recreational spinner might not notice it, but it is easily perceptible to somebody that pays attention to their production rate.
Mostly I like the quiet. I do not know how much of that is the new bearings and how much of that is changes in the maidens. At this point, the it is ugly, but I like to make things work before I try to make them pretty.
Why do I keep going back to bobbin speed?
Because speed is critical to fun spinning. If the wheel is too slow then spinning becomes tedious.
A while back, a local guild passed out 20 g samples of cotton and asked us to spin a couple of hundred yards (long draw) of cotton yarn. The other day a spinner from that guild said she was not enjoying spinning that cotton. I can see why. Her wheel is too slow. It is taking her forever spin that bit of cotton. And spinning long draw has a rhythm, if your wheel is too slow (or too fast) you lose rhythm and it is much harder. Two hundred yard of long draw @ 5 tpi is (or should be) half an hour's spinning. I had it done by the time I got up from my wheel at the end of the meeting. When I got home, I wound it on a reel and boiled it while I had a cup of tea with my wife.
I am not bragging about how fast I spin, I am pointing out that modern wheels are made to spin slowly. Wheels can be made to spin faster.