One more thing I would like to add...
I really do like friction shifting and in my younger years I could hit it everytime. In more recent times I have found myself missing the shift when going down and up where there is an underpass. Since I pre-shift before coming up the other side, I don't know the engagement because there is no load on the pedals (I don't want to have to back pedal each time) and I just don't want to be off and have the chain jump if I get out of the saddle. It also seems to be a little tougher to hit everything perfect after I installed a Sachs freewheel. I do have to admit that I am enjoying index shifting on my road bike for the first time since it was introduced 30 years ago.
As far as friction, Simplex shifters are great, but I actually prefer the old cheap Shimano L-422 spring loaded shifters. I modded some to work on my down tube bosses and removed the ratcheting ring and they were lights out for me.
John