While I feel I get very nice results with my V700, I will have always wondered (and will keep wondering) if I could get better results with a Coolscan. If there's anyone out there who is willing, I'd love to mail someone a few negatives to scan so that I can see if I will actually notice any difference in the images I take.
If you are happy with the results, I would suggest that you
don't compare it.
Whether or not you will actually notice a difference will depend on a lot of factors. In terms of actual detail resolved - if you use good film, good equipment, good technique and the subject matter has enough actual distinguishable data, then of course you will. The examples below show the same frame of Fuji Velvia 50 - taken in controlled setting, scanned with the Epson V500, V700 and Coolscan.
Full size Epson V500 ->
http://www.fototime.com/33269E445D10043/orig.jpg
Fullsize Epson V700 ->
http://www.fototime.com/11F59FA46FF9497/orig.jpg
Fullsize Coolscan ->
http://www.fototime.com/02BB797801DCA89/orig.jpg
If you really want to see if your scanners is resolving all the details captured on your frame of film, you can invest in something like a 40X microscope/loupe. What you can visually see with this the Coolscan can resolve.
This came in handy as I scanned some slides from a pro - 70's & 80's Kodachrome, and he was unhappy with them because they were not critically focused. I proved to him it was his film that was not focused and not the Coolscan's fault.
BTW, the details realized by the scans above - in this case, are not the limits of the film but the scanners.
Of the tens of thousands of various frames of films that I have scanned, detail/sharpness is great but for the most part you can apply the amount of sharpening you need for the purpose - print or post. However, color and contrast can take far more time to adjust in post if the scan doesn't get it right or at least get you in the ballpark. And this is really where Coolscan+Nikonscan truly shines compared to all the other scanning methods (hardware/software) I have tried. For instance the differences in some cases can be is so vast that you would not even think they are the same frame of film.
This one using Kodak Ektar 100 with the Coolscan and Epson V700
This one of Kodak Gold 100 with the Coolscan and mini-lab Noritsu
I have many results from all other scanners compared to the Coolscan+Nikonscan but these extreme differences don't happen too often as most discrepancies are more subtle.