hehe. Turbo Power vs. Blast Processing. Are there any technical specs showing which is more powerful.
Well duh! Blast Processing isn't even real! Nintendo proved that! So of course Turbo Power wins HANDS DOWN!!!
As far as which to buy- Well I am in a somewhat similar situation: I have a US Duo with some sound issues, So I just bought a PCE DuoR because it was the least expensive.
With your US Duo you can play US Turbo Chips
And with your Japanese Duo you can play US CD/ US SCD/ JP HuCard/ JP CD/ JP SCD
So your pretty much covered.
If you go the US Duo rout again, you would need to pick up an adapter to play JP HuCards, assuming you do NOT have a HuCard converter to play JP games =)
Get the Duo R, it looks super awesome!!