From my own experience imaging surface mount circuit boards, MSX is somewhat useless since once you have adjusted the focus to allow the thermal imager to be a few inches from the PCB, the MSX overlay is too far offset and you can adjust it far enough to overlay correctly.
That means turning off MSX and then you need a lot more pixels than 80x60 to be able to get a good idea of what component you are looking at. Besides 80x60 is pretty hopeless in general (without MSX).
So, for my use, the E4+ (E8 resolution) is basically the minimum (and sufficient) for looking at components that are 0603 is smaller. The E4+ is a very useful tool *IF* you need to thermal image things, otherwise it's another 'come in handy one day gadget'...
cheers,
george.