What is the maximum memory limit for a MacBook mid-2010 with the latest EFI and SMC updates? According to Apple, the mid-2010 MacBook (not MacBook Pro) will support a maximum of 4GB of memory.

I am seeing some references like this one which indicate that the latest SMC and EFI updates allow for more memory. 

Are there any more authoritative references to more than 4GB of memory working in this model of MacBook?

What is the safe and cheap path to verify this myself? Can I get a single 4GB chip, replace one of my 1GB chips and see if the supported total memory is 4GB or 5GB? Worst case I've just bought the maximum 4GB, best case I prove that it can take more right?
If it's indeed the last model of white polycarbonate "unibody" MacBook that Apple made prior to the discontinuation of the MacBook (non-Pro/non-Air) lineup then it will actually support 16GB of RAM (2x8GB PC8500 DDR3 1066MHz SO-DIMM 204 Pin) and that's vouched for by the specs for that system in MacTracker as well as by the reliable folks at OWC.

You'll want to verify your exact model identifier via the System Information app though (this app also used to be called System Profiler in older versions of Mac OS X). 

Open up that application, select "Hardware" at the top of the sidebar pane, then look for "Model Identifier" on the right. If it reads MacBook7,1 and your "Processor Speed" is 2.4 GHz then you're good to go for 16GB of memory!