Seires 5 8bit/??bit Color processing From 32" Up
Series 6 10bit/12bit Color processing From 32" Up
Series 7 10bit/16bit Color processing From 32" Up (Actually A750 don't have a 32" but you get the idea)
Difference for 32" vs Higher is the DCR numbers and without AMP 120Hz
I have both A550 and A650, and hell who ever said you can't tell between 10bit and 8bit is a lie.
You can test it with places which has many color layers and also test it with low resolution with lower bitrates videos with both monitors and you will see that 10bit has better image over 8bit. 10bit has smoother image and better color spreading. You can also test it with the GT5P and DMC4.
There is one way u can't tell the difference is to step far far far away.