The Sean Terrill site is pretty cool. Probably my favorite thing about the internet is you can almost instantly find the answers to any "I wonder if. . ." questions. I haven't tried to trick MrMalty yet, but I plan to look into that.
From my pen-and-paper calculations based on the chart in "Yeast", I think doing one smack pack with 100b cells, a 2L > 4L stepped starter would yield 430b cells, while 100b cells in an 8L starter would yield 400b total cells. So you'll get marginally more yeast, and use 2L less wort, but have a little bit more hassle. Of course, I was never a great math student, so I could be wrong.