I see no problem with it since you seem to know what you are getting into. I hope she makes you a very nice little companion horse.
As for the poster that talked about breeding a valueless horse? Not necessarily. If a foal is born out of 2 winning parents and has winning brothers and sisters but suffers an injury during their youth that makes them unsound for riding, it isn't such a bad thing to breed them if they can physically stand it. I have a very good friend who owns a stud out of Doc O'Lena and Gays Sugar Doll. Very good parents who both either won good money themselves or their offspring was money earners. Unfortunately, Fajita suffered a leg injury as a foal that made it impossible to ride him. He was used strictly as a breeding stud and has sired at least 23 money earners plus many priceless ranch horses.
Anyway, back on point. Tasia, I hope it all works out for you and if you get her, I want to see some pix of her 'homely' self.