To me it's like the last time I bought tires. At the tire store they tell me they take 35 psi but when I look at what's embossed on the tire, it says 40-45 psi. Thank you very much, but I think the company that made the tire knows more about it than the guy who put it on my car.
Just to play "Devil's Advocate" -
Do you also only use Window's Firewall and only Window's disc partitioner and only Windows Defender - no outside software for these Windows built in utilities?
In spite of the problem I posted above (I blame myself and think PD probably had nothing to do with it), I used Perfect Disk for 4 years with my XP, and it seemed to do a very good job. Does Vista do a "good enough" job? Maybe, but the way I see it - to extend your analogy - when you get a root canal done to you want to have it done by your local dentist who does 8-10 a year, or would you rather have it done by an endodontist who specializes in it and does 8-10 a week? (As someone who has had a lot of root canals - and some very bad ones by dentists who think they know but really don't - I can tell you, in the case of root canals: go to an endodontist! Make of that what you will. )