Jim,
If it's the same genetic marker that produces the long-coat in Rotties, it can be tested for. We did that with Presley and Juneau in our last litter because Juneau is a Rowdy granddaughter and Presley is a Magic son and Rowdy's long-coated litter was out of Magic. Both Juneau and Presley are free of having the trait or carrying the recessive gene.

That behavioral thing about dogs with the coats being longer/softer is true. I've known over a dozen long-coated Rotties and each one was a total doll. Our Harry Potter is exceptionally sweet. One warning though: the longer coats are a bit of a pain to maintain. Harry's is very fine and mats easily. So we take him down about every 6 weeks or so.

Good luck with the search and have fun with lots of puppies. That's the really fun thing about the process.

Jim