Great review! I agree with you, all the Bernina Records are heavy, and I have a 900 Nova as my portable. I think the 700 and 800 Sport are even lighter. There are lots of light weights to choose from these days, but few are worth considering as your all-in-one machine. The stitch length lever on the 930 is different than the earlier models. My Nova has a simple revers button. As mentioned, the 930 came with extra strong motor and all the stitch patterns, I guess it's bound to be heavier.
The 930 does a nice buttonhole, it's a basic straight shape only and you have to draw a line on the fabric to set length. With a bit of test sewing you will get the hang of it. You can easily do a corded buttonhole with it, and I guess the Pfaff should be up to the same.
If you are very picky and want thicker thread, decorative keyhole shape, and perfect zigzagging you might need a dedicated buttonholer model, but you should be able to make nice buttonholes on either of your machine. I have to say I like the buttonholers I have for my Singer 201, one of them has a few key shaped cams.
You end up keeping them both?