I like the idea of the quick scene change - maybe also available for music if WA5 gives some support for quick search. The gemstone effect could be done quite easily i think - i may have a go when i get some free time.
What do you mean by more texture support in r4? also, the visual feedback effect in r4 has been there since the first public beta. You *really* need that new gfx card :p
I never noticed any colour change in the gemstones - it was always green for me

Still, r4 will do changing colour - things like sabretooth and chris' redbluerings have dynamic changes in colour:
R2e actually had an effect very similar to gemstones. I forget what it was called now. It kindof pulled the visuals into squares and faded to black - one version panned around too.
- Gordon