Quote Originally Posted by clayne View Post
Not necessarily - most of the "entry level" color film is (and always has been) more than capable of producing solid output.
Sure. But the pro films are (sometimes much) better again and the difference is quite visible in an 8x12" print from 35mm. If they weren't better, they wouldn't exist and be sold at 3x the price...

For example, Portra 400 has grain as fine as Reala and is 2 stops faster. Pro160S and Portra 160 have about twice the linear resolution (so about 4 times the total info content recorded) of any Gold or Superia class film, let alone the really cheap stuff. Ektar is even finer again, but you get nuclear colour.

6x4s aren't going to look much different and if that's all you print, don't bother with pro films. If you want to make a 12x18" enlargement, the quality change is arguably the difference between grainy technicolor mush and a pretty fine print.