Several weeks ago I had the honor to receive a Paint Jack to test from DJL Tools. The other day I got to give a test run. I thought to myself how could this thing work? Would it stay in place? Would it make painting faster?
Well the answer is YES to all. It works wonderfully. It stayed in place and did not budge. I think it does speed up painting by maybe 5% but this is hard to judge. Since you do not have the bail in the way it makes painting easier. 
I have been painting for over 25 years and never have seen anything like the Paint Jack. I will now be recycling some of my old paint cans so I can use the Paint Jack when ever I work off a ladder brushing on paint. Thanks Dave for inventing this great little device and for making them in the USA. I wish you much success.