Is it much heavier than the large Veneta? And the proportions, is it about the same?
I used to own a Sloane in nappa capri (nappa, but rolled and perhaps tumbled, to achieve a glowing sheen and silky drape). I currently own a medium Veneta and a large Veneta, both in nappa.
To the best of my recollection:
-The Sloane was noticeably heavier in the hand and in actual weight, but when placed on the shoulder, it didn't feel too burdensome. The wide, pliable shoulder strap distributed the weight nicely. But while I'd describe the Veneta as being a lightweight bag, I wouldn't characterize the Sloane that way.
-As for proportions, as you know, the Sloane is boxy while the Veneta is slim. On the shoulder, the Sloane made me feel like I had sumptuous draping leather under my arm--my arm rested on it.
-Sloane is pillowy, while the Veneta is more streamlined and geometric on the bottom corners.
-The Sloane has an ample armhole/shoulder drop, but the top of the "box" is still palpable. The Veneta, both medium and large, feel like I had nothing under my arm, because I usually pushed it back behind me. I know some have trouble with the armhole on the medium Veneta, but for me, if I push down the zippers on both bags to form the armholes, both sizes have a lot of shoulder drop room. My arm feels unencumbered.
-More on the proportions: the Sloane sat up higher on the body, similar to the medium Veneta. The large Veneta, with its longer strap, sits lower.
-Capacity: I think the Sloane and large Veneta can hold similar amounts of stuff, but I've never directly compared the two.
I'm 5'2" and slender (between 100-105lbs, currently), so your impressions may vary. For me, it came down to this:
-medium Veneta, nero: able to be dressy enough to wear with business attire, can go day to night, doesn't look like a huge sack
-large Veneta, ebano: comfortable, casual bag that can carry more than the medium Veneta (can be dressier on taller women)
-Sloane, nero: dressier than large Veneta, but more casual than the medium Veneta; heavier than both Venetas, lacked a top zipper
I ended up letting go of the Sloane because when I wanted to carry a nero bag, I almost always chose the medium Veneta over it. The streamlined, geometic shape of the Veneta fits better with my wardrobe, too. But the Sloane is a great choice, too.