Dual Sided DVD Burner/Media question

Hello,
I have a QuickSilver G4 single 800Mhz desktop and a Dual 2Ghz G5. Both have DVD burners but are outdated. (Pioneer 105 and 106 burners)
I want to replace the internal drives with an internal Dual Sided DVD burners. Here are my questions:
1) Can someone recommend a Brand and Model of burner that will work within these two computers without compatibility issues? (I guess my preferred brand would be Pioneer as that is what is in them now)
2) Which media should I buy? I currently use DVD-R and have been told to stay away from the DVD+R media (at least in the world of Single Sided Media) When I switch to a dual sided burner, what media should I buy then?

Thanks in advance,

Chris M.