Default 8.4 vs 10.5

I currently own the S 8.4 LTE, but somebody fell in love with it and wants to buy it from me for pretty much the price i bought it for (somebody visiting me from another country who can't wait for a new one to be delivered), so far i like the tablet and i am using it as my main phone (don't make many phone calls with it and when i do i use bluetooth) and the rest is basically emailing and IM(ing).
So if i sell this one to this person i was considering the 10.5. I understand that with a larger form factor some other difficulties come up (portability and such) but apart from that fact, anyone owns (or have used) both of them and could give me a reason to go for 10.5?
How is picture quality with lower pixel density? Does RGB makes a DIfference at this resolution vs Pentile in terms of Image Quality? Handling?

Thanks.