Agree with everything everyone has said....
A lot of the so-called research which has "shown" solid colours to have more behavioural issues has been incredibly unscientific in method and anecdotal in content.
I recently skimmed through one article on "Cocker Rage" which had a case study of a pup bought from "a well known London department store" who started growling when food was "repossesed" from him (at something like 11 weeks old) - "behaviour modification" was initially successful, and items could be "repossessed" at any time, but then he started biting... Pup was eventually PTS.... aside from the fact that this was resource guarding, not Rage, the fact that he was sold in a pet-shop, and whatever method they used for "behaviour modification" (if it worked initially but then the behaviour escalated, I'd be willing to bet it was at least confrontational, if not out and out aversive) are far more relevant issues than the fact that he was a male solid gold pup! However stories like this are used to show that solid colours have more behaviour issues....

As others have said, as long as the pup is raised in a good environment, and both parents have good temperaments, colour really isn't an issue. What has complicated the issue in the past is that "bad" breeders have bred for specific colours (without consideration of temperament) so these colours became associated with the temperament issues... but that doesn't mean the colour caused the temperament issue, just that both traits (a particular colour and a poor temperament) were passed down through the breeding...
