I was told there is a limit of 255 folders a device can sync from the mailfile. Is this true? Anyone know...

Mailfile? If you mean the number of email messages then the limit is the practical limit for memory. I have had 2300 emails on the BB at one time.
Keep in mind the more memory is used for simple storage the less effective the Blackberry is in handling application operations. If you mean added folders to the blackberry such as folder to store other files or apps in then again the limit is the memory. I cannot understand why you would want to have more than 255 folders anyway. The Blackberry or any other smart phone is not a pc and simply maneuvering that much information would be very time consuming.

At some point you have to look at how you work and how you use your BlackBerry. Syncing 255 folders is going to tax ANY handheld device. I don't know if there is a folder limit, but if there is a limit, just approaching it will undoubtedly slow down your BlackBerry's performance.

Free internal memory remains the critical factor in performance. No matter how many folders you have, keep a weather eye on the free memory of your device.

I did some research and could not locate any limit so I agree with rambo47, the BB will become useless if you load it up to the max.