I have done a few conversions in PS and am really pleased with the results. Even a sepia tone type print that looks great. But I still wish I had taken them in B&W. It's partly just a hunch but I think an excellent B&W conversion will not be as good as an excellently exposed and processed and printed B&W. Since we expose B&W film differently,namely expose for the shadow detail rather than exposing for highlights in trannys, which is what I mostly shoot I don't think you can make up for that in PS conversion. That being said, one problem with B&W is that there just isn't as much silver anymore so I don't know that we'll ever match the old masters.
All that being said you can make really good B&W prints with converting in PS that people will love but ultimately perhaps not as great as a truly great B&W. But...how good is good enough?
Strong recommendation: find a good supplier who stocks both and will allow you to run some test scans, and try out both units using your own negs. The response of different scanners to retained-silver emulsions is very dependent upon light source, and the Minolta 5400 (which I have) produces some very hard, grainy, contrasty scans thanks to it's hard, cold-cathode light source. The Grain Dissolver feature of the 5400 works to some extent, but the change isn't very great. The LED-based illuminants in the Nikon may prove to be less severe, but note that in general Nikon scanners are still considered to be quite hard on the grain.
If you can afford it, the forthcoming 9000-ED (like the outgoing 8000 model) still uses LEDs but apparently provides considerably more diffuse illumination. Also, don't dismiss the new Epson flatbed, the Perfection 4870. I tried the previous model (3200) and while it didn't meet my requirements for colour and was a bit unpredictable for B&W, the best of the B&W scans were creamy smooth and delicate in their tones. If the new unit actually include proper exposure control rather than purely post-scan adjustments, it might be worth a look.
In saying this, I should add that I'm not trying to suggest that a scanner is necessarily bad because it has a hard light source; it's all a matter of what you're going for. If you plan to shoot Tri-X and want hard, gritty prints in a 1970's photojournalistic style, then the Minolta may suit your purposes just fine. Also, it is possible to calm down the contrast of Minolta scans with a bit of judicious curve control, although there's not much that you can do about its inherent graininess other than use a grain-reduction program (which can have side-effects you may not want) or just bite the bullet and apply a bit of blur to the file. However, life will be a lot easier if you buy a scanner that churns out a look that you find pleasing right off the bat, so it's worth taking the time and trouble to do some evaluations on your own negs.
I appreciate your comments. I am still not sure which equipment to purchase. I have a feeling that this is a "no lose" situation, as both are superb products. I need to see some scanned B&W photos to make a determination, as that is my primary medium. I have found out that the Coolscans are relatively hard to find and in high demand. I doubt that there will be little opportunity to do any testing. May be the classic "shot in the dark" type of situation. By the way, any opinions on the Zeiss 17-35 Zoom for the Contax N1? I am unwilling to purchase a proline digital camera at this time, as I feel they are rapidly evolving. Besides, some scans I have seen absolutely are incredible.
Joe (not Jack)
You're right, it is a "no lose" situation to a certain extent, but it's still possible to be disappointed depending upon how picky you are. If you want to see some s&le B&W scans from the 5400, you'll find some in my review here:
I would imagine a bit of web trawling will dredge up some LS-5000 s&les too, so that will let you do some sort of a comparison. What film do you shoot mainly BTW?
Re the 17-35 I'm afraid I can't comment, not being an N-system user, but I'm sure there are plenty of folks 'round here who'll be able to assist. I wouldn't mind betting it's a better lens than anything Canon has to offer at this focal length, anyway.
I have just bought the Minolta and it is very good, although Mark is correct, the scans are 'hard'. The minolta scan software doesn't work properly (it doesn't recognise the scanner every time) on my Mac (OS 10.3.4) if that's a consideration for you, which means shelling out more money for software. It's fine on the PC though.