Never pre-order, but then it just depends on need. I mean, I'm not going to get an older CPU, because the new one might have bugs. So, if a new one came out, that'll be it. But, I'm also not going to go buy it because it's new. I'm going to buy it because I have a use for it.
The exception, however, is Linux boxes. It's always better to be a little behind the latest and greatest, to not have to deal with hardware teething issues in the kernel.
If cost were no object, I'd go with Xeon E5 series all the way, equipped with more RAM than I know what to do with, VMs included, using a custom passive water cooling setup, and a single case fan for mobo/GPU components. Cost really needs to remain an object .