Usually I would advise to make sure that unstrapping/strapping up Kellys would not be cumbersome for you, but in your case you are used to it with the J. B30 is really such a versatile bag, it is somewhere between a purse and a tote and can do the work of both with some editing. I think part of the issue with the B35 was that you had a firmer/thicker/heavier leather bag and a vintage one to try since it was Ardennes. With B35, the leather matters so much, they are like completely different bags. A B35 in a firmer or thicker leather will be more like luggage as you say, and very huge/jutting out on petite frames like ours. Now if you take a clemence bag on the other end of the spectrum, it is much softer and looks so much more proportional on shorter frames (IMO). If you have the chance to try a B35 in clemence, or even a thinner togo, I would absolutely still give that a try. Swift would do the same, but it may be a bit saggy in B35 over time. Clemence/Togo just looks so chic in that size when it gets worn in, just my two cents worth. For B30, most leathers will be fine since the size is much smaller than B35 (it is closer to B25 in capacity for me than compared to B35), but the same rule applies - stiffer/firmer leathers will have more of the "jutting"/suitcase effect compared to softer leathers.