(Mid-, I'm here! My workday nearly killed me
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Hikarupanda, if you're comparing the small Cabat with the large Capri, I'm not sure that the Cabat is that much more open. I've never seen a Capri in real life, but my sense is that it has a simple fastening at the midsection only. The way I carry my Cabat on my shoulder, my arm falls over the midsection exactly where the closure would be on the Capri. Both bags would be open on the ends. I don't know how the Capri compares to the Cabat lengthwise, but when I'm wearing my Cabat on the shoulder, it's actually not that open because the bag ends up being snug against my body as I carry it.
Ottone and platino ossidato are very different in personality, I think (I've compared them in person side-by-side). It's hard to recommend colors to others because it's all a matter of personal taste. They're both excellent choices, so it really depends on the look you want.
As goldenflower mentioned, the platino ossidato is very durable (it's Barcelona calf, not nappa). I wanted a workhorse bag, and I'm glad I chose it--it has a weathered appearance and a very sturdy feel. That said, it's heavier than nappa. Ottone is goatskin, and it, too, is heavier than nappa, I think.
Doing an SO large ottone Capri or going with a small platino ossidato Cabat--both are going to be significant investments, so if there's any way you could see the colors and/or try on a Cabat, I'd encourage you to do so. I was fortunate enough to be able to see and try on my platino ossidato Cabat before buying, and that helped a lot. I love the simplicity of the Cabat and I like the easy access with the open top. But it's your bag, and if you're not comfortable with the Cabat design, don't spend the moola on it and go with the large Capri instead.
Good luck deciding!