I usually prefer small sedans to small hatchbacks because a sedan boot is usually larger, self-contained and separated from the cabin compared to a hatch. I'd wondered exactly why the BA had such a useful load space for a hatch. I think I've finally figured it out and I believe it's for two reasons:
a) The sloping rear window (as opposed to upright like on most hatches) allows a sedan-like boot space,
b) The full hatch opening allows excellent use of that space to load bulky items.
Both 3s I have are sedans with folding seats too. However whilst the load length (to the front seats) is longer in the 3s, the loading is limited by the fixed rear parcel shelf and arch separating the boot/cabin spaces. The BL2 has a more restrictive boot/cabin aperture due to a larger/stronger arch (I'm guessing for rigidity/safety reasons) compared to the BK.
My last effort to fit a kayak in the BA showed me that the length to the front seat is not *quite* as long as both my Mazda 3 sedans but the hatch opening made up for that.
[img]http://i1222.photobucket.com/albums/dd490/pitrack_1/1994%20Mazda%20323%20Astina/kayak1_med_zpsdxfcwrsz.jpg[/img]
Also, the loading of the following item into the 323 was impossible in the 3 due to the aforementioned parcel shelf/arch, but no problem (except for a little length) in the 323.
[img]http://i1222.photobucket.com/albums/dd490/pitrack_1/1994%20Mazda%20323%20Astina/shelving_transport_zpsc39kpy0z.jpg[/img]
I don't know about [i]ANYTHING[/i], but pretty darn useful

[b]Patrick[/b]