I think the problem is no one is willing to do their research. The turf lines are proven mainly because they are so successful in Europe not only on turf but over jumps. Jump racing is huge in Europe which many fail to realize.
LOTS of excellent lines out there to study and find prospects from; just have to be willing to look. In America, a lot of the turf lines are tried on dirt because dirt racing is more popular here. Doesn’t always work out.
I’ve done the research and expanding my knowledge base is extremely important to me. I go to the sales regularly (KEE, FTK, OBS) and study LOTS of horses, trying to match physical features with recent ancestors in the pedigree. I hunt for “sport type” and the stallions that tend to produce that most often. (I also hang out at the jog strip at Rolex, taking confo photos and honing my eye for how 4* horses are made.)
I look for stallions who stamp, and those who don’t (let the mare come through). I look at yearlings, mares, weanlings, and horses of racing age. I put most emphasis on the horse’s overall balance, proportions, front end, and its walk. Of course the hind end is important, but honestly it’s not usually a weakness in race-bred TBs. Most often, they have a big butt with a low shoulder and a level way of going; not what I want. I’m looking for an uphill neckset and a high point of shoulder with a long humerus; personally, I’ve found that to be important and a fairly common trait among successful upper level eventers.
I hunt for TBs with that shoulder, and I pay very close attention to where it may have come from in the pedigree. I take notes and compile them into spreadsheets, so I can track various sires and their conformational tendencies. “N=1” is the biggest weakness in our TB Sport Horse equation-- you need a big sample size to make accurate assessments of what a stallion produces (otherwise, how do you know it isn’t the mare?). I don’t develop a firm opinion on a stallion until I’ve seen at least 5+ examples (10+ is better).
From viewing many hundreds of horses in person, I’m starting to have a pretty good grasp on what I like, what I don’t like, stallions to follow, and stallions to avoid. True, 99% of the horses I’ve seen are unproven in sport other than racing. However, I think conformation plays a big part in how a horse moves and performs. So I’m on a quest to find the conformation that I think is best suited to an upper level event horse and the stallions who produce it; I feel this is useful even if I don’t have current knowledge of direct offspring successful in sport. I’m not particularly looking to breed to any of these stallions, but rather have an idea of what they produce so I can shop effectively in the OTTB market.
In the spirit of this thread, I put my money where my mouth is and in 2012 bred my upper level event mare to a TB race stallion, Sightseeing. I chose him because I liked the horse’s conformation, I liked his pedigree for sport (Pulpit/AP Indy over Pleasant Colony mare), and I saw dozens of his yearlings/2yos who were VERY CONSISTENT in type, in a way that suited my mare. The resulting TB foal is coming 4, and just did his first XC school on Saturday. https://youtu.be/uaoTsplQ01o
He’s smaller than I’d hoped (15.3; mom is 16.1 sire was 16.3) but conformationally, he’s just about what I expected. He’s very well balanced with a lovely front end, strong hip, athletic, and better to ride on the flat than his mother. He has some cheeky, naughty moments, and he finds jumping to be boringly easy (though I haven’t jumped him over anything significant to know how scopey he is). I am happy with my breeding decision and how it is turning out. As for why I chose a racing stallion over a Sport TB, it came down to pedigree, prepotency, and what I felt would compliment my mare to produce my ideal type.