Given your local (I lived in Vista and dad was in Fallbrook) I can comment directly. We had a smaller Tuff Shed put in for dad so my comments are more shed related than barn related. They are like Foster Grant sunglasses. Foster Grant took the bargain sunglass market and made a science out of it. Their product is more likely to fit more people than probably any other inexpensive sunglasses. they just plain do a better job at it than most.
The Tuff Shed is the same in the pop-up building market. They will not win any Fine Homebuilding awards per se. However, it arrived in good shape, went up quick and was finished off by the installers as good as any tract home in a general area neighborhood in SoCal (better than some, in fact). We did run electrical and lighting, put in linoleum floor and skin the walls in 3/8" plywood. It has served dad quite well and looks like it will survive in our mild climate for as long as the house.
"A hen is only an egg's way of making another egg".
– Samuel Butler