I've replaced my rear derailleur with a brand new Acera long cage which I got from the bikehub.
No more skipping in any gear! However, on my ride home, I did notice some ghost shifting just once. Otherwise, everything was good.
I think I can chalk that up to this derailleur not being designed around non indexed shifting. It is much more picky about line tension in each gear versus my old suntour.
I'll get a pic tommorow.