While I still haven't made the move to a Treo 755p yet, I did finally change my current Treo to sync with my work Outlook instead of Palm Desktop. For a long time I've been keeping two calendars manually to keep my work and personal calendars separate (but synchronized). My personal calendar (Palm Desktop) would sync with my Treo so I had to copy all my work appointments into that to stay updated. This is of course a horrible approach.
So, I made the move to use Outlook as my primary calendar. It syncs with my Palm and is always current for my work events. The only problem now is keeping in sync with my Google Calendar that I use for personal appointments and to share with my family.
So my new process is:
Use Outlook for work.
Use Google for personal.
Synchronize the two so that each has BOTH work and personal appointments.
Synchronize Outlook with the Treo so it has ALL my appointments.
Since Outlook and Google don't support this type of sync out of the box I had to find a tool to help. So far gSyncit seems to be working fine. It is only $9.99 but has a free (nag) trial that you can use.
I've used it for a day or so and I'm still pretty happy. At first it was fairly painful, but after cleaning up the initial duplicates and issues, it seems to be sycning fine without errors. By default it syncs every 15 minutes which I found to be way too aggressive. I think I have it set to every two hours now. I've found that it seems to hang up and get pretty slow on occasion but since it executes in the background (or at least doesn't steal focus) it isn't too big of deal.