Is my horse to old to begin training?

[Minaxminax@aol.com]

I am in Colorado and leasing a saddlebred gelding (and seriously thinking about purchasing him) who is 9 yrs old that I have begun to train for endurance riding.  He is an excellent trail horse and loves to trot everywhere.  What is everyone's opinion on begininng to train for competition when the horse is 9?  

By the way I worked him at a trot for 6 miles straight a couple of days ago and his pulse was a good rate and he recovered very fast.  

I don't know if this is a factor, but I'll throw it in as well...he is blue blood with world champion saddlebreds in his bloodline, I won't write his value, but it is high.  He seems to be the right horse for my endurance riding, but I am new to endurance riding.  I only want to do what is best for him and make sure I am making a sound financial decision by purchasing him.

Thanks guys!