I have a coming 5y.o. Furstenball gelding. Length of pasterns and their angles and strength, and balance in relation to overall leg length and body size/mass, that is what is important. What I noticed is that when Furstenball offspring is young, they grow full length pasterns first and very fast, and so at inspection they look kind of longish. However, as offspring matures to 2-4y.o., bones in legs grow and balance the ratio out. Pasterns are long enough to create the spring and elasticity of the ground, but they are also strong enough and have good angles - all you need for a dressage horse. Would I choose such offspring as jumpers? Probably I would want to see a tad shorter pasterns for a jumper. But Furstenball is a dressage stallion for dressage breeding, right? So…
Well except that Furstenball himself could not make it to the top of the sport (dressage) due to unsoundness. The length is not the real problem- but the strength. Furstenball did not get past PSG and needed to be retired at a fairly young age. He has been shown in hand in the last year or two with egg bar shoes behind, presumably to try to give him support for his dropping pasterns. So pasterns certainly a concern to dressage horses as well as jumpers. 
That said, he is a stallion I love and the offspring we have had by him have been some of my favorites to sit on. He has a lot to offer as a stallion, plenty of excellent qualities, and our Furstenballs have not had pastern issues themselves, either, but it’s certainly not something I would shame breeders for considering.
The mare I bred this year had a Furstenball foal as her first I believe. Anyone here know of a gelding named First Light? I think he was a 2013 foal but could be wrong.
