ekincam - some thought the numbers you showed on the UOA at 4400 miles on the Toyota were outstanding. (indeed, some of the recent base dino UOAs are putting out numbers as good as Mobil 1). looks like your blend is one of those. so, how do you expect to do any better? perhaps your question is primarily directed to the cost of the Mobil?
if its the cost, "they" also suggested running the 7500 mile Mobil, well, more than 4400 miles.
personally, i don't think i would change motor oil if i got a UOA like you did. not to a blend synthetic or even a full synthetic. anyway, some on here, believe the Pennzoil with PureBase is a Group II+ ($1.73/qt at Wal-Mart). its corporate twin, QS, is suppose to be a Group II. i don't know about others as II+. the Pennzoil UOAs have been v. good, although there have been very good recent Exxon's SuperFlo, Castrol's, etc., and makes one wonder if every major brand dino motor oil is pretty good.