I use both these derailleurs almost daily. The Nuovo Record has a lighter touch and performs just fine on a 6-speed 14-30 cog freewheel, and the Blueline feels more solid but requires more muscle to move over a 14-32 cog freewheel.
Admittedly, some of that is certainly due to the shifters. (NR shifters on the NR deraileur, BL shifters on the BL.) Also, the NR setup has the better 8-speed chain.
__________________
● 1971 Grandis SL ● 1972 Lambert Grand Prix frankenbike ● 1972 Raleigh Super Course fixie ● 1973 Nishiki Semi-Pro ● 1979 Motobecane Grand Jubile ●1980 Apollo "Legnano" ● 1984 Peugeot Vagabond ● 1985 Shogun Prairie Breaker ● 1986 Merckx Super Corsa ● 1987 Schwinn Tempo ● 1988 Schwinn Voyageur ● 1989 Bottechia Team ADR replica ● 1990 Cannondale ST600 ● 1993 Technium RT600 ● 1996 Kona Lava Dome ●