Hey Jon,
In a very quick comparison of just 6" kindle ereaders on the market as of right now, there are 4 different ereaders and all 4 of them are different sizes and weights.
They range from 5.6 by 4.8 inches all the way up to 6.7 by 4.6 inches. With respectively 6.3 by 4.5 and 6.4 by 4.5 inches in between.
Oh and for anyone curious the weights range from 4.6 oz to 7.6 oz.
So even just within one brand and size screen there is a pretty good size difference.
Actual chart.
https://www.amazon.com/b/?node=66697...pf_rd_i=Kindle
For fun went and looked at the Kobos.
All their 6" vary a bit in size too.
And yes the 5 inch mini is still listed.