I'm also not, did paint only with my graphire4 (4:3 Format) since 2006 - until 2011 with 4:3 screens and from 2011 until today with my old graphire but with an 16:9/16:10 screen. But I think a wide Format Tablet - is a bit better - because it will fit better the wide-screen
But I will have bit better results with an intuos
... my graphire I wll use with my old IBM-Thinkpad-Laptop
I will look now for an Intuos A5 Wide-Format / PTZ631 Model c:
An A4 Model would be also to big for my Desktop, A5 Size or A5 Wide Size is fine enough
CONS / PROS for A4 and A5
Pro A4
A4 = more precision
Cons A4
A4 = more arm movement
A4 = to big for my desktop
Cons A5
A5 = less precision, but this is not so bad, you can should use zoomfucntions for more precision
Pro A5
A5 = less arm-movement
A5 = not to big for my desktop
btw. I see also on E*ye - that intuos3 A4 are cheaper than A5 .... it means, the most people like a5 sized tablets.