For $1500 you can get dogs from much more accomplished breedings than these. In my opinion that price is way inflated for what I'm seeing here.
Long-coated GSDs do not, to my knowledge, carry genetic ailments. That said, a breeder who is specifically aiming to produce long coats may be sacrificing other things in order to focus on that particular trait, so I would be a little more cautious in evaluating such a breeder.
Yes, you can compete and title in performance events (such as agility) with limited registration. The only event you'd be restricted from is conformation showing, which would be a complete waste of time and money with these dogs anyway.
ARCHMX TDCH Pongu the Insane, CD-C, RE, RL1X6, RL2X5, RL3X2 (GSD mix, b. Apr 2010)
Crookytail the Tigerwuff, RL1, ITD (Akita mix, b. Jan 2011)