This is just my opinion / speculation ..but in my hhead proven doesn't mean much when looking at boys. Sure, he bred no problem to the female he was paired with prior, but even with a proven boy there is no guarantee he's going to go for your girl. I've heard from a few different people that sometimes two snakes just don't jive. I would rather buy boys that are of superior quality than to get one because it's "proven". If the pastel boy is a great looking pastel and awesome example, I'd go for it. If it's middle of the road I wouldn't. This is just my opinion, take from it what you will. Good luck!