copper pipe system...I had just about fought down the urge to build it and then you have to post a thread all about it....
lol.
I have given this a bit of thought and I think there could be some advantages to it if it were done correctly. Also, with the right setup, switching out components wouldn't be that hard -- I have semi-tested a method for having copper pipe that still allows changing out components like heatercores, pumps and waterblocks and it works well.
advantages - no chance of tubes kinking, slightly better flow rates, looks very cool.
problems - obviously more expensive, obviously more work. the conductivity (thermal or electrical) can be dealt with easily enough so I don't consider that a problem.
some general ideas on setting it up, some tools that would help and how it could still allow for changing out components:
obviously, anytime to you have to resort to radical angles, you loose some flow. The 90 degree copper elbows would be a no-go for max flow. damn, that kinda rhymed...Anyway, that would leave the 45 degree elbows as one possible solution for taking corners - you could add a 45 then a short section of copper pipe and another 45 elbow to get a 90 degree turn that wouldn't have as much of a flow rate hit but there is a better way to handle that -- the 1/2 copper pipe bender...add some more $$ to the expense list but it you are going to go all out on this, get a pipe bender. All you have to do is take a look at some of the hardcore pipe work done by the custom phase change guys to realize that you can do stuff with copper pipe that is nothing short of artwork - some of the copper pipe work on the custom cascade systems is flat out amazing. You wouldn't need anything as extreme as the loops they create for phase change but a copper pipe bender would allow you to create loop that had smooth curves for all of the bends required and sections of the loop between components could be made from one piece each so so there wouldn't be any seams....and it would get rid of a good deal of work with the torch. Once the copper pipe was bent, you could bracket it to the floors and walls of the case to keep it in place.
leaving a way to change out components:
this is simple and effective.
Get the copper pipe bent out for each section between components but leave it to where it stops about 2" short of where you plan to mount your individual components. 1/2" ID tygon or clearflex can be stretched over 1/2" ID copper pipe so just make the last 2" jump from the copper pipe to the heatercore, waterblock and pump with tygon or clearflex and then use metal hose clamps to lock the tygon or clearflex in place. a short, straight section of flexible tubing isn't going to screw up anything and it would provide a way to swap out components and take the components off if they needed to be cleaned.
If you were really concerned about shorting something out with the copper pipe, you could coat it with a spray-on rubber coating like rubberized undercoating used on cars. Liquid electric tape would work as well.
If you have everything bracketed to the case, I doubt it would be a problem in the first place.