I just went through a similar decision process, and have decided to breed. I think it would be awsome for you to have a foal out of your beloved mare. Also, rest is good for an endurance horse, so months off for the mare may be benificial, even if it's delivering and chasing around a snot nose baby. My mare and I haven't officially started our endurance career (so this is advice coming from a newbie), but I'm using the time to do a lot of long slow miles while she comes to term. I guess that;s not as applicable to you, since you already have rides under the belt. My thoughts are, overall, the cost and time is worth the effort, because for once I will have a horse (in the long run) who I have known from birth, and won't come with excess baggage, often mysterious.
Laura "Not all who wander are lost." (jrr tolkien)
