Measuring Sugar at bottling

I normally add the priming sugar to a bucket then bottle. But, sometimes I only want to bottle a six-pack and keg the rest. In those situations I have used the coopers drops and it worked fine, but I do not always have them. A long time ago I bought the little measuring scoop from Mr. Beer that is supposed to measure the exact amount for one bottle. The have a small scoop for a 12oz bottle and a larger scoop for 22oz bottles. It is designed to measure the same amount each time and to pour into the bottle without making a mess.

Just curious if anybody has ever tried one or something similar?

http://www.mrbeer.com/product-exec/product_id/69/nm/Sugar_Measure_1

how does this work? I wqould be interested also. I party pig half my batch and bottle the rest. Right now I use a Priming Sugar spreadsheet (found somewhere on HBT) that calculates your amount of sugar to add to bottling bucket based on your desired CO2 level.

My only drawbacks are 1) you have to estimate the amount of beer being bottled based off the lines on your bucket/carboy 2) carb level can vary based on ambient temperature, at least from what I have read.