I’ve been listening to DNR since the beginning (232 shows), and this was definitely one of my top ten favorite shows. Very interesting discussion. Congrats!
I just listened to this radio show, and I think you did a great job. There was one point that I wanted to make about the compile time point that you mentioned. Although the cumulative time of the compiling is something to consider, I think that the hesitation that it puts into the developer to compile (I am a PHP developer so save and refresh) is another reason to opt for more RAM and a better CPU. Especially when running Unit Tests. The less painful it is to do it, the more likely a developer is to do it early and often.
Later.