My sgp 4.0 has been retired to just music and gps and a little facebook while on the go while my main device now is a samsung galaxy tab 2 7.0. The SGP 4 is still in great shape I bought another 16 gb card to store the music. I got the tab because it is easier to type notes on for school and watching long videos on the 4.0 gave me a headache on occasion. If I plan to replace one of these it will probably be around a time when I can afford a decent smart phone so I will likely do that.
I also wouldn't mind a 8 inch tablet I don't really care too much about an extra inch but still a 10 inch tablet in my opinion is too big to justify carrying around instead of my laptop