My problem with the 43 folders was that they added complexity to the system. The tickler was one more thing to check and maintain. Wouldn't it be just as easy to make a note on the calendar--"pay electric bill"--and to file the document in a "bills to pay" folder? You're already maintaining a calendar and alphabetical filing system. So why introduce a third level of complexity?
I would even suggest that the method above allows for a little bit more control over material. Let's say, for instance, that it's the middle of the month and I want to get a sense of where I'll be at financially at the end of the month. It's a lot easier to pull out a "bills to pay" folder and review all my bills at once than it is to rifle through a tickler file.
Likewise, let's say that I have a document I need to bring to a meeting on 4/28. If I file it in the tickler, what happens if someone calls me about the document or asks me to photocopy for them ASAP? Granted, it's probably easy enough to go to my calendar and remember that I had filed the document away in the tickler for a particular meeting. But wouldn't it be just as easy to file it in an alphabetical system and then to jot down a reminder on my calendar to bring file/document X to the meeting?
The tickler is particularly problematic if you and your partner/spouse both need access to your bills for review, payment, etc. In that case, your best bet is to have a common place where you keep your bills to pay and to put reminders on your calendar.
Finally, I personally found the tickler made it way too easy to defer making decisions on stuff--especially random junk like magazine offers, events, etc. I would pull this stuff out of the tickler, look at it, and then put it a week later. Weirdly enough, the act of deferring this stuff was actually somewhat stressful--it made me feel like I was procrastinating on stuff that wasn't really important. Without the tickler, I'm forced to make a decision: either throw it away, create an action/project, or put the item on an incubate list. Making this decision reduces the stress. For me, at least, the tickler actually encouraged the habits of postponing decisions that GTD is supposed to overcome. I can't give myself the luxury of that out.
That said, a lot of the comments here have made a very strong case for the tickler.