Yep - still a 25% shot at a visual BEL in your Butter Pastel x Mojave pairing. More genes don't decrease your chances at hitting anything - it only increases your chances at hitting more genes. I'd venture to say that most BELs created are by happy accident in multi-gene pairings.

12.5% Normal
12.5% Mojave
12.5% Pastel
12.5% Pastave
12.5% Butter
12.5% Butter Mojave (visual BEL)
12.5% Butter Pastel
12.5% Butter Mojave Pastel (visual BEL)