none I prefer good distances ! but I would rather have a drastic long spot than a drastic deep spot though because crashing into the fence is not fun ( from experience)
It really depends on how you ride, how you distribute the weight on the horse, and how much control you have over your horse. I rode a 15 h horse the other day in flat and he was great. I think the most important quote is : " heels down, look up and don't ride like a potato"