Both posts bring up the same analogy, attributed to Matt Cutts:
Nofollowing your internals can affect your ranking in Google, but it’s a 2nd order effect.
My analogy is: suppose you’ve got $100. Would you rather work on getting $300, or would you spend your time planning how to spend your $100 more wisely.
Spending the $100 more wisely is a matter of good site architecture (and nofollowing/sculpting PageRank if you want). But most people would benefit more from looking at how to get to the $300 level.
While I agree in theory, I think that’s a bit oversimplified. What if you could re-allocate your $100 more effectively in just a few minutes, then go try to raise it to $300?
Sculpting PageRank is one of those things that can earn a nice benefit in a short period of time, but you can keep tweaking forever for progressively lesser and lesser gains. See the chart on the left.
Knock out a few of those links, then spend your time trying to work on getting $300.