Pure white BP's in all thier varieties are gorgeous. I do however understand why not many try to add other genes to a pure white snake. More that likely you will still just have a pure white snake that you will have to raise up to breeding size and breed to another snake before you know what you have. How do you price a hatchling if you don't know what it is?
The exception would be to breed something like a lesser/lesser BEL to a SUPER pastel lesser. Any resulting BELs would be guaranteed to be pastel as well, so you could price them accordingly.
Then there is the chance that some pattern morphs might bleed through and show up on a lucy. Personally I think the dirtier BELs like super mojos have more potential for this. I know I would love to see a pure white snake with a purple clown or spider or pinstripe pattern. I admire anyone willing to invest the time/money into a project like this and "think outside the box".