When you get your papers post the ped and then we could tell you about those dogs in the pedigree. However Blu is a good looking Kennel I am sure if you talked to the breeder they could tell you what you want to know about your dogs lines as I sure they know them better than we do wince they are producing from them and do not look to be breeders that just put dogs together without thought. I have seen some dogs from this kennel and they are very well put together.
As far as Knuckles and RE thats opinion. The RE dogs you often seen with Gaff are well bred dogs and used in breeding programs the work with AKC and UKC type dogs. Many are UKC and/or AKC titled dogs. They are not bullies. Now those that feel anything that is not gamebred would say they are. These dogs are bred just like the Gaff dogs for more bone however they are not out crossed with mastiff or any other dog for size. They are Pittterstaff more than anything and thats only if you consider the Amstaff/APBT split, which again comes to personal opinion. I highly doubt any of the RE this kennel has are current day dogs, they are most likely the pre 90's Amstaff RE dogs that were foundation for the RE Bullies.