I currently use Mendeley and have been happy with its organisational capabilities. However, I would like to be able to make freehand annotations and drawings on pdfs, which Mendeley does not support. I've downloaded a trial version of Papers, but I am finding its metadata input extremely clunky and error prone compared to Mendeley. I would like to be able to sync between iPad and Mac easily. Can anyone recommend a good reference manager that supports freehand pdf annotation?