Joined: Oct 2008
Posts: 1,313
Likes: 1
From: Örebro, Sweden
Bikes: Monark sportser 1970, Monark sportser 1970ish, Monark folder, Mustand 1985, Monark Tempo 1999, Monark 318 1975, Crescent 319 1979, Crescent 325 c:a 1965, Crescent Starren 2002 (hybrid/sport), Nordstjernan 1960`s cruiser.
Your assumption matches mine; "full size" are more comfortable on relaxed rides. A wee bit undersize are somewhat easier to handle on long and speedy runs. "Modern" geometry and sizing in road bikes leans to undersizing (compact geometry) so I gather the outcome in performance should be the same for older frames. I prefer 60/61 c/t frames to my old-school-sizing-should-be-63 cm measurement.