A six speed freewheel's biggest flaw is that it has only six speeds, and that's not so bad. Shimano came out with six speed cassettehubs, which were a true breakthrough, but then they tossed most of its advantages by going to seven, eight, nine, and ten speeds. I still ride six speed freewheels.

And I still like single pivot brake calipers. So you don't beat me at curmudgeonliness. Let me think about my stable. I don't have the list in a file...

1971 Super Course, with everything replaced. Six speed freewheel and Mafac brakes
1973 Raleigh Twenty, with everything original. Brakes suck.
1967 Hercules 3-speed, with everything original. Brakes work in the dry but not the wet.
1982 McLean racing bike, with mostly Campy Nuovo Record, six speed freewheel, and Campy Record single pivot brakes. The brakes are excellent.
1991 Cannondale M700, mostly original. But I never ride this, and it's disassembled.
2008 Surly Cross Check, with brifters and cantilever brakes. Lovely. Yes, I love the brifters, but I don't like the price or lack of durability. I got the drivetrain used.
2008 Nashbar generic fixie with two dual pivot brakes. Aluminum frame. A darned serviceable bike with nice handling and road feel. Only $300 for the whole bike.

Wow, I have seven bikes I call my own. That's crazy. But I can't think of what to get rid of.