As an owner of the Mach II GT, I can tell you that phase change is not something you use every day. I am sure there are going to be several people who purchase the Cryo-Z with the hopes of using it for day-to-day computer tasks, and if you bring a set of earplugs this might be something you can pull off. As for me, I will stick with using phase change for when I am looking to make a really good 3DMark run. Phase change computing tends to do very well when going for a top ten record as long as you have the additional hardware to push into the extreme overclock territory.
When looking at the Cryo-Z and comparing it to the Mach II GT, several differences stand out. The mounting system for the Cryo-Z is much better and you do not have to purchase additional hardware to mount the system to different motherboard platforms. Also, since the Cryo-Z uses foam instead of the black sticky thread (goop) you end up with a motherboard that does not have a permanent mess all over it. Both the Mach II GT and OCZ Technology Cryo-Z cool the processor right around the same, even though they use different compressors. When it comes to cost the Mach II GT is around 899 US Dollars and the referee is still out on the Cryo-Z, but I would expect the final cost to be lower than 499 US Dollars.
The biggest problem I have with the Cryo-Z is the build quality. If the rumors are true then it is this reason why we are just now starting to see these coolers being made available to the public. If all of the units OCZ has in stock are like our sample then there will be a few people who are not going to be satisfied with the product based on appearance alone. OCZ is going to have to be creative with selling these units. Maybe a disclaimer to the case's build quality will need to be put on PC Power's website or another run of cases can be made. Many enthusiasts have taken their Mach II products and placed them inside Lian Li V2000 cases, a conversion that takes little effort. Maybe OCZ can purchase a number of V2000 cases and make the best phase change cooler ever by doing the mod themselves and bundling the case with the phase change system, and delivering it to enthusiasts under a 599 price point.