We adopted Jenny in July of this year. She'll be two on November 24th and the youngest Greyhound we've had. Our first, Wendy, was already two when we adopted her. Our Lola was 4 when she came home. Wendy raced a bit, Lola not at all, and Jenny a bit. To be honest, I don't she a huge difference as far as behavior. Wendy was the poster dog for Greyhound adoption; a Mary Poppins, if you will - practically perfect in every way. Lola, the oldest of the bunch, was the most challenging; hard to house break and with severe separation anxiety. Jenny, the youngest, has been challenging to house break and had mild separation anxiety. All three girls were about equally energetic, happy, sweet and goofy. Jenny has been a bit destructive, chewing on the edge of furniture, eating one panel of the vertical blinds and stealing my glasses (I keep them out of reach now!) but has since adjusted well.
I really think that each dog is a world unto itself, each with his/her own temperament and personality. Hope your pup is a good match!