I have both the CS (level wind) Mag Elite and the BG. The BG has a more solid feel to it. It's also easier to work on, getting the magnetic strip back on the Mag is like getting the dog spring in a Squidder to seat right
The mag really isn't necessary on the level wind models, the centrifugal brakes and the level wind combine to slow the spool enough. I've seen you cast both your 965 and 975, and the 975 is a "hotter" reel than the BG. You know how to cast, you really don't need the mag. Sand gets into the groove that the slider control rides along, too. For the difference in price, which now really isn't all that much, I think the BG is built just a little more solidly. Swapping the baitcaster handle for the power one just about covers that little difference in price, anyway.