Sorry for arriving late to this conversation. Been a busy week. Anyways...................
The Glenn Frey signatures do look a bit "suspect". The Joe Walsh and Randy Meisner's are a really good match (Meisner has been dropping letters from his last name signature for quite some time), the Henley signature is really a close match to what I see him sign (keep in mind, his signature has stayed close to the same for most of his career) and the Don Felder's though a bit rushed (on the Hotel California item) is still very good. I question the Glenn Frey, though if it isn't his, its a pretty fair reproduction.