I bought my really good, leather, high-quality used saddle for my horse when I bought her. It has a 15" seat, I believe (I don't think I went with a 16), and it is big (and heavy) and deep and so secure that it is pretty well impossible to come out of (indeed, I haven't yet in the two years I've been using it).
Then, more recently, I came into possession of my sister's old, beat up "tester" saddle that has really seen some years. It's certainly the least aesthetically pleasing saddle you could imagine, it's curling and worn, has no fancy trimmings and, compared to my other saddle, as light as a feather. However, I just feel more...right in this saddle, moreso than the other.
The big saddle is great and secure and makes you feel safe, but I feel kind of...restricted in it, if that makes sense. In the little saddle, I just feel more active and in control, even if the saddle itself is not as deep and secure. I don't know what seat size the little saddle is, but it's definitely smaller, and it feels more suited to me.
I don't really know what the point of this thread was, except to ask: is it really possible to have a TOO big saddle (for you)? I don't know what I'm going to do with the big saddle-I've taken to riding in the smaller one all the time, no matter what horse I ride, but I'm not sure if I should sell it or keep it. Perhaps I could sell it and get an equally nice saddle, but with a smaller seat? I'm not sure...I really like the saddle, I like how secure it feels, but it's hard for me to really ride in it.