I definitely vote for the small MP. I have two of them, and they are absolutely perfect, very light and easy to manage. I just bought my first Blake on eBay (authenticated here) last week, and although it is drop-dead beautiful, it is too heavy for me to manage easily and I am going to resell it on eBay. Too bad, because the style is so gorgeous! It truely is one of the nicest looking bags I have ever purchased. So if the weight doesn't bother you, go for the Blake. I think I am definitely the minority here on tPF~ people seem to be happy to deal with the weight of the bag, because it is so awesome looking. Depends on what matters to you.
Good Luck!