Inkpad 4 vs 3 in terms of contrast and lighting?

Hi,

I have Inkpad 3 and because of annoyingly uneven front-light, I seriously consider upgrading to Inkpad 4. But some comments on decreased contrast and continuation of unevenness issue keep me holding.

For those who own both, could you please compare (preferably by photos) the two devices in terms of contrast and front-light distribution?

Thanks .