QH Endurance....

Thanks for everything you've said jillybean! I don't have any interest in competitve trail. It's nothing like endurance riding. I just want to ride for hours with my best friend (my horse), win or lose it doesn't really matter to me. Of course I would be fine placing in the top 10. :) I know it takes time to condition, but I'm not expecting to go out and have him do a 50m. I know he wouldn't be able to do that. I am totally fine sticking with the LD rides. That seems like something we could do with some conditioning work, no problem. He just loves to trail ride. If we were just trail riding he could do it all day (at a walk). He is so level headed and always wants to please. We get alone great, so I would never want to use another horse even if its a better breed. I do have a Arab/QH or a TB/QH, we don't know for sure because she was a rescue and has no papers. She has great energy, but she sweats so much, is a little unsure on her feet, and I just don't trust her enough yet. So even though everything else other then my horse would be better, I wouldn't trade him for the world.
As for having them lay down so you can go to the bathroom, that's funny!! :)

I think there is a balance between discouraging people from trying endurance and encouraging them to have realistic goals. My first thought when looking at the OP's horse was similar to Joe4D's in that the horse is too heavily muscled to do more than LD.

Fortunately, I doubt the horse would come to harm by any ambition the rider may have, no matter how unrealistic, because a horse built like that is just not going to hurt himself by going too far or too fast. The rider would wear out far sooner by trying to get him into a pace that would mean he finishes in time.

The grade QH that was posted as a successful endurance horse is not built the same but has leaner type muscles. He is built more like a TB. The OP's horse appears to have halter type muscles that are big and bulky. I feel it is kind to point out to people who may not realize all that endurance entails that their horse may not be suitable. If you have read Endurance Granny's Blogspot you can learn about the frustrations and pitfalls of trying to condition a non-suitable horse for LDs.

I have a friend who managed to get a Paint mare through an LD ride but it was tough. The horse kept up with the Arabians and SB cross but was mentally fried by the end. She started trying to quit after about 18 miles and it was hard to push her through even though there was nothing wrong with her. She was as fit as she could possibly be for her body type and leaned down, but she hated it.

You make a valid point here that while a horse may be capable, some may simply HATE it - including Arabs. If you don't have a horse that wants to do it, then you're going to have a miserable time pushing them through it. I do have a few friends who've described their horses simply shutting down at a certain distance, and the rest of the ride was hell. And these were mostly Arabs! (not that Arabs are more likely to do this, but that most of my friends have Arabs)

I have competed on an arab, a OTTB and an appaloosa. All had the desire to do it.

My friend competed and placed in Ctr and endurance on a VERY stocky arab x qh. He didn't pulse down quite as fast, but he could go forever and had the desire to do so.

I say if you want to know how he'll do, take him out asap and start putting miles on him. When he's in decent shape, find a trail about 20 miles, take him out and do a mini endurance race, seeing how quickly you can finish at a pace he can maintain. It will also show you if he really has the drive to do it.

What ride will you be doing in April? Are you in the SouthEast?

I'm in the North/West, it's the Grizzly Mountain ride.