Bob, I have both a 1600 and a 178 that I use with my Esprit 100 (550mm F/L).
I find the 1600 is just collects signal more quickly (larger pixels) and calibrates very consistently, whereas the 178 has some whacky amp glow that makes it more challenging. The dark frames I've seen from a 183 are similarly haunted.
The objects you want to chase would no doubt be better served by a larger scope than I'm using, in which case I'd say it swings in favour of the 1600. The reality of the conditions in SE QLD the majority of the time means that we'd be really lucky to see any improvement in resolution with the smaller pixels of the 178/183, and they're a bigger hassle to use
