See to me it is more logical to spend time thinking and designing rather than making/buying many different blocks.

Your point on water temps is well-taken. With a GOOD heatercore (large facial area and low flow resistance) one should get water reasonably close to room temp. That isn't going to be enough IMO to make up for all design flaws; you'll want much cooler water for that. However, going below room temp is a relatively expensive proposition not necessarily in terms of part cost (dehumidifiers and such) but in terms of time to build and energy inputs (cost to run). This winter (coming soon) I am definitely taking advantage of the -40C cold outside though and switching from a traditional H2O system to a "big ass res outside with barbs through the window" approach :)

Does going with chilled water affect the aluminum vs. copper issue any?

Yes and No. Yes because: I seen that people do not want to use AL because it cannot handle higher overclocks because of the high wattages, but if you cool the water I don't see how that would still be an issue because the block would be able to handle a much higher wattage would it not?

No: Because that still doesn't change the thermal charicteristics of Copper and Copper should still cool better, but to a much less importance I would think.

Hopefully this will not cause any big fights, but what I gleaned from my previous (ill-fated and now locked) thread is that copper will always perform somewhat better than aluminum, but that the difference is minimized under certain conditions:
1. Higher flow block design (wider, deeper channels with big pump)
2. Thinner base plate
3. Less concentrated heat source (larger die size with less O/C and voltage)

I don't think chilling the water will materially affect this to any great extent.

Bob

If you could come up with an affordable chiller I agree that it could make you a profit but you still need a block for the chilled water to flow through so that market is still there, -10C or -12C would still be on the mind of the extreme:)