I have an 885. which i love and also the wife gets on with. The newest version of the software is very good and Logitech telephone support is also great (free phone number).
I have not used the 785 but did have a 525 which i believe is the same thing but with out the colour screen or charger. The 525 eats batteries for a pass time.
I have been running the 885 for18 months now no problems.
I am in a similar situation. I can't see any benfits other than asthetics between these two models. To be fair the only benefit I can see over going for the cheapo 525 model is a colour screen and a charger.
The same software and the same buttons seem to be in place on all models apart from the 1000 series. On this basis I have ordered the cheap one, hopefully I won't be disappointed
The layout of the 525 and 885 are different even if they have the same buttons.... but the 885 in my opinion has a much better layout... it is bigger so can use chunkier buttons and therefore easier to press and see. Once you have one in your hand you quickly realise how much logically laid out the 885 is (even if still not quite to my liking) & how easy it is to press the right buttons without needing to check. I was struck by how the Play/rewind/pause etc buttons just came to hand, which is what you need! I also believe it handles more devices.