I'll echo this experience. I used to run my own MX, and it was constant work to stay current enough to keep spam to barely acceptable levels. Constant work.
Since switching to Google apps, however, I almost never see spam. I even run a wildcard for my domain (with a blacklist for egregious offenders - every company gets a unique address) and still it's 1000 times better than when I was doing it myself - for no time investment at all. All for 'free' (letting Google read my mail is the true cost).
Not sure what the OP is talking about.