Jelco 750D or 750L?

Is there any real advantage to using the 12" version of this arm compared to the 9" version? I plan to use a Lyra Clavis Da Capo or AT-OC9ML. Table can handle either size.

My question relates to effective mass and sound qualities more than geometry.

There is a theoretical advantage, but I don't think a real advantage. I asked that question about a year ago on another forum. I ended up with the 750D and I am happy and a couple of hundred dollars richer.
I got the 10" 750E as a compromise, and couldn't be happier with it.