Great going Mike.
One (of the many!) frustrating things I find about chin-ups, is that unlike press-ups, where you can momentarily 'hover', when nearing failure, before that extra effort to complete the rep, with chin-ups I have to put my feet on the ground as locking my arms at the bottom, is too strength sapping. Once my feet hit the ground I feel it nullifies (cheats) the attempt on the next rep, as it makes it relatively too easy.