12" disc usefulness

[alexmin]

I am buying a 12" disc. I already have 9" beveled steel disc from KMG. While I like it sometimes I feel I need a 12" disc.
I use it to make sure flat grind is really flat. I love how it makes any irregularities pop up on a flat grind. It let me improve my results a lot.
Also I use my disc to handles and scales

I wonder if anyone one else is using 12" discs and finds it useful.

Thanks,
Alex