Testing for doneness in jelly-making

I've always used my Joy of Cooking's instructions for testing for doneness in making jelly. Joy of Cooking recommends the sheeting test, which you hold a spoonful of cooked jelly above the saucepan about a foot (out of the reach of the steam), and turn the edge of the spoon slightly and watch for the jelly to "sheet" off the edge of the spoon (two drops that come together and fall off the spoon as one). 

I had always wondered if there wasn't a way that I could use my candy thermometer for testing doneness, and just this week found out, yes, I can use temperature to test. I like the idea of using a thermometer, as it seems much more precise. With the sheeting method I could never be sure if my jelly was indeed "sheeting", or not. 

To test using temperature, boil the fruit juice, sugar and lemon juice (if required), until the mixture reaches the temperatures given for the altitude in the table below. This comes from the National Center for Home Food Preservation (http://nchfp.uga.edu). If you are unsure of your altitude, err on the side of a lower elevation (higher finished temperature). I'm between Sea Level and 1000 ft. I cooked my latest two batches on Sunday, to 220 degrees F.

And by the way, I've been using the temperature test for jams as well, with much success.

Temperature Test - Use a jelly or candy thermometer and boil until mixture reaches the following temperatures at altitudes of:
Sea Level	1,000 ft	2,000 ft	3,000 ft	4,000 ft	5,000 ft	6,000 ft	7,000 ft	8,000 ft
220° F/ 104 C	218° F/ 103 C	216° F/ 102 C	214° F/ 101 C	212° F/100 C	211° F/ 99 C	209° F/ 98 C	207° F/ 97C	205° F/ 96 C