Beyond the particulars of each specific camera and how they may handle cards formatted on other devices, there are also benefits to regularly formatting flash type memory.
Bad sectors are mapped out by the card's controller.
Most memory cards have a bit more memory than their listed capacity. When a bad sector is identified, the memory controller will block the use of the bad sector and replace it with some of the 'spare' memory on the card. One of the common differences between top name brand memory cards and generic/no name memory cards is the number of bad sectors mapped out of the card's total memory before it leaves the factory. The greater the amount of memory that must be mapped out, the less reserve memory is available on the card for the controller to use as other sectors fail later on. All of the major brands (Lexar, SanDisk, Transcend, Kingston, etc.) get their components from the same handful of suppliers that actually manufacture the memory chips and controller chips. So do the off-brand names, but they usually buy the leftover components that may or may not have been good enough to pass the QC of the major brands' buyers. One of the thing the buyers look at is how much reserve memory remains on the chips after the bad sectors have been mapped out at the factory.
Another advantage of regular formatting is better wear leveling performance.
The way flash memory cards (and USB flash drives) work is that the memory controller on the card assigns different areas of the card for specific directory locations each time the card is formatted. They do this for what is known as load balancing/wear leveling.
Flash memory has a limited number of write cycles it can tolerate before it fails. The number of write cycles each bit on a flash memory card can handle before it fails is very large but it will eventually wear out. So the controller tries to ensure that each storage location of the entire card is written to roughly the same number of times over the life of the card. What this means is that even after you format the card the controller will continue using parts of the card that have not yet been written to until each storage location on the entire card has been written to before it will go back and begin using the locations that have already been used.
Formatting regularly helps the memory controller on the card do a better job of wear leveling. If you leave the same files on half the card and repeatedly write files to the other half, erase them, and rewrite other files then all of the wear is going to go to only half the card and the life expectancy of the card before half of it fails will be shorter!
Formatting also allows for better card performance by increasing the likelihood of sequential write operations.
