I can't really say for sure- I am not th keenest on picking out breeds ( well, I know Arabians...LOL)
BUT that horse really looks like Rom at the barn I go to- and Rom is a Arabian/quarter horse mix.
The only pic I have to show of Rom is from the website, and its not very good- but the second photo you provided looks like Rom- head shape looks the same, and what you have been saying from others telling you, would make sense. I am no expert at all though. But sure enough- spaz looks like Rom! Yes, they are both white...lol, but I think other aspects look very similar. I can always snap some pics of Rom for comparison, though, I don't know if there is any way to be 100% sure- I think bloodwork maybe? I simply don't know Spring Creek Farm - Lessons
( he is the white horse in the first picture)