I currently use the Aquaview enlarger with my D200 housing - which I have been told will work with the new housings for the D3 and D300, so I intend on continuing to use it. For me, it was well worth the expense, as it really helped with focusing with macro shots, and with framing on my wide angle shots. I haven't used the INON 45 deg finder, so I can't say how well it performs. The way I see it is there are benefits to having the 45 degree or the straight on enlarger. The 45 deg can be beneficial if you're shooting a lot of macro so you don't have to drop down as low if you're in a tight place, but I think I'd still prefer the straight on for shooting wide as it seems to be easier to me to eye a shot and then frame it the way I see with the straight on finder.