Is the zoom size for icons going to remain capped out at 256px when magnified? Are there plans to increase the zoom size of icons? I may be interested in purchasing the Ultimate upgrade by I have to be convinced that it's worth it to me. So far it does indeed blow Object Dock out of the water in all aspects.
With the free version my icons seem to not be as high quality as they are when viewing them outside of the NeXus application. With the Ultimate version will my icons appear at a higher resolution?

Icon quality remains the same in the free and paid versions. Quality also has to do with the mouse over effect you are using *and* if you are using a PNG or ICO file (icon files usually have multiple fixed-size versions of the same image, PNG files, on the other hand, have a fixed image size which must then be either magnified or scaled down).

256 x 256 is the biggest size available. I don't think any other dock uses larger sizes either.