[Linada]

I think the lack of a general PIM for Macs is partly philosophy. The general idea is to pull things apart, while making them work well with each other, rather than creating a big do-it-all program.
My experience is that the core OSX applications(Mail, iCal, addressbook etc) are good for keeping things in sync and getting data out, but when you are trying to get more data in, they hit their limits. The lack of start dates is a symptom of this.
Incidentally I am not sure what you describe as Apple Sync. I am guessing you mean MobileMe. The Core application do sync directly through mobileme with all their limits, OF can sync itself either via WiFi or for example iDisk, which would help preserve data across multiple machines.

To be honest i have never really seen the need for an integrated PIM. Switching applications is to me a bit like switching context. And the integration usually makes it unnecessary to switch until you are ready to. You can clip a task from safari or mail, as you know. Spotlight is pretty good at quickly finding things, and tools such as quicksilver and Google quick search can launch apps and perform actions, such as starting to write an email, pretty quickly from anywhere.