Delcour, what is it you're looking to accomplish? If you're looking to understand if potential vendors are sufficiently drying their beans, the items you note could work for that - but i've never used those ones personally. I have had great success in working with Dickey John Mini GAC units - and it should be noted that the units you've posted (and the mini gac) will likely require a calibration curve to be loaded for it to correctly interpret the 'atmosphere' around the grain or seeds that it specifically is being used for - so you'll want to look closely at those units to see if they've got cacao specific calibration curves available. Alternatively, i know folks have also used aqua boy moisture meters - and i've tried them myself, but find them far too bulky and less accurate, plus i had to answer a lot of silly security questions when airport police scanned my luggage.
I'd concur with Brad on the value of a good knife. a guillotine may be useful for you to do an assessment at home quickly, but you'll find it very expensive and a knife will give you the same results.