As a prosumer, I have been "on the fence" between MacPro and iMac for the last 6 months. Now that the iMac Extreme is available, it is hard to justify the MacPro. However the hard drive on the iMac has 8 GB of cache and I am considering replacing it with a drive that offers 16MB of cache. Hard drive upgrades (after purchase) are not available by any apple store, etc. You open it, NO WARRANTY, period. So that said... decision time. Do you A) Buy the warranty and just deal with the drive? or B) Not buy the warranty, open it up and replace the drive, deal with any consequences down the road? Opinions?