What I do is I use both systems depending on what the item actually is.
I use a physical tickler system for things like meeting notes, parking tickets, invitations, etc. Things that physically land in my inbox but I'm not sure whether I am going to act on it yet. So I incubate these things in my physical tickler folder system.
For other input that isn't necessarily tangible, I put an outlook entry as an all day event preceded by a "!" mark. So I know immediately that this is just a tickler item and not to think about it unless it occurs on the current day, at which point I immediately drag and drop it into my e-inbox (which is just a list of tasks in outlook that have not been categarized yet).
This functions identically as a physical tickler; it just saves me the trouble of writing something on an index card just to throw into a folder. It also makes it convenient to drag emails onto certain days.
This has been working great for me. I was also concerned with whether to use a physical tickler or an electronic one or both. I also wanted to retain the hard edges of what the calender is supposed to be. Since the ! catches my eye the first thing in the morning when I look at that day, I immediately drag it into my inbox and there is never an issue as to what is a tickler item and what is a must-do for that day.
Hope that helps somewhat.