I did get a mini because I feel it's small enough that it won't get dinged up too easily. Also you can at least buff away some of the scratches on lambskin. I took my boy caviar woc out a handful of times and I already rubbed the edges of the flap somehow. I was pretty upset over that and since it's caviar, once it's scratched, it's scratched.... luckily it's just the edge. Granted, I don't think I'd get a light colored lambskin bag, but I think the darker colored ones in a small form factor is fine.
Editing to add - it barely rains where I'm at so I don't really take that into consideration. I guess if I lived somewhere rainy then I probably would stay away from lambskin lol.