The neck dimensions are different between the 8270, 8470 and 8670. The 8270 has the standard 2005 prestige neck dimensions. The 8470 is 1mm thinner hence the titanium. The 8670 is about 1mm narrower but about 1.5mm thicker than the 8270 and has two substantial strips of bubinga (a kind of rosewood) which look great and probably contribute to the tone ? The 8670 has an
ebony fretboard the others are rosewood - a matter of personal taste- ebony gives a brighter tone, not a better tone imho. It does however make the tree of life inlay stand out very nicely being darker !The 8270 has a striped ebony
headstock overlay, the other two flamed maple. The 8270 has no neck binding. If we're talking about the RG8470F as opposed to the RG8470A (which doesn't have neck binding either !! ) then from what I've seen on Japanese websites the tops are very mediocre and the new colours are disappointing, but may look better with better flame tops.The tree of life inlay on the 8470 has more mother of pearl too i.e. the stem. To me the deciding factor would be the quality of the top !!! You pays yer money and makes yer choice.........