Why would you want to change out all those hoses. Have you run on the smaller and you didn't like the cooling or were you still running too hot. People always pick on Koolance because of hose size. And some of the se people have never owned a Koolance.
I purchased a Koolance PC2-601 13 months ago and I run 27-31 degrees celsuis all the time. After playing games for hours it's a constant temp. By going to 1/2 inch hoses, what do you really gain, 2 to 4 degrees cooler. Do you know for sure?
I purchased mt second Koolance PC2-650 a month ago and I have a P4-3.2E Prescott overclocked so far to 3.8GHz and it runs 29-31 celsuis all the time. I will push 4 Ghz real soon with better Corsair memory.
Yes the size does make some difference, and yes, there are many companies who sell water-cooling systems. Give Koolance a chance with those smaller diameter hoses.
ROJAS