Always a good idea to get pairs from the same line if you have any intention of breeding. Outcrossing inevitably throws unwanted traits into a line. And you can go a good 6 generations before you have to outcross because of inbreeding problems.
Yes I agree especailly sents the EBD is not a strong line. If his line is health and breding then it's a strong and health line. I'd be 100% totally happy with a sibling pr. Just like with my HMPKs a sibling pr is fine as long as there not enter bred 5 or 6 times.
I have never bred anything BUT siblings. As people said, with the EB gene being very rare, you would need to get 5 or 6 from the same parents to get a breeding pair when they are older.