I have one of those small ones too... And they're cool. I don't usually carry it riding, but it stays in my purse. ecurbh usually carries a leatherman tool too, that has lots of handy gadgets on it... The think I like about that big equestrian knife is the knife is really sturdy, the blade locks in place, and it's very sharp. You could cut a big rope with it, it's a real knife unlike some small pocket knives that you can't really get a strong grip on.
Yes, the big knife looks like a serious knife. I can't remember if mine has a philips on it, I don't think so.