@Science Officer - cool beans. And they seem to have some more reference material too
Should be interesting to see how accurate Tobias makes it.
It's entirely possible that the Enterprise have the same saucer diameter. I did a comparison and posted on a different thread but will copy over here soon where I did a top-view matched-diameter comparison. The only catch on that one is that perspective on the two ships could be off enough where the bridge modules might appear to be different sizes.
If they have the same diameter saucers, then the Reliant ends up with ~6% more volume than the Enterprise. If I can find good pics where the docking ports are clearly visible on both ships I think it'd point to roughly how large the Reliant is.
Interestingly, in a post by one of DS9's production crew, they scaled their CG Mirandas to 560' which is alot smaller than the roughly 700' or so if they had matched diameter saucers...