Here's my example. Most of my travel is between SEA and YWG, let's say once a month. I'm frugal and will not pay anything other than cheapest T+ fare.
Under 2010 system, I'd get 2x SSWU, use them on a round-trip, and that would be the end of it. My NAUs and SWUs would be wallpaper except for the summer / Christmas promos.
Under 2011 system, I chose 25 eCerts + tier bonus. 12 r/t SEA-YVR-YWG works out to 39,888 miles. Let's assume I do one trip on UA via DEN to hit 40k, I'd earn another 20 eCerts. With 45 eCerts total I can upgrade 7x YVR-YWG flights.
New system is clearly a winner in this scenario.
Let's throw in some other travel. Suppose I have a business trip to NRT, and I fly SEA-YVR-NRT r/t. My company will only pay lowest economy fare, so I use 28 eCerts to upgrade YVR-NRT r/t. I still have 17 leftover to upgrade another 2x YVR-YWG flights. eCerts are still a winner.
Cancel the NRT trip and replace it with a trip to LHR, flying SEA-YVR-LHR. That'll cost me 34 eCerts to upgrade, 11 leftover, still enough to upgrade 1x YVR-YWG. eCerts win again.
The only downside I see in my situation is that if my overseas trip happens earlier in the year, before I've hit the 20k threshold, I won't have enough certs to upgrade it both directions.