I have a few Epson scanners, and I'm very familiar -- and comfortable wth -- Epson Scan. 've tried the demo versions of both VueScan and Silverfast, and I have issues with both. With Silverfast, the user interface is confusing to me, and I was only able to get scans by apparent accident. With VueScan, some of the menu items were clipped off, so I couldn't read what they said (indicating to me a lack of attention when designing the interface), and I was never able to find a way to do batch scans of slides where I have adjusted exposure to different levels for various members of the batch. It wanted to apply the adjustments to every member of the batch. I dunno if I was doing something wrong, or if VueScan can't handle individual adjustments in batch mode, but in any case, I was dissatisfied with both, didn't really see any difference in scan quality between either one and Epson Scan, so I just decided to save my money and keep using good ol' ES.
To answer Iridium, well for the first question, I gotta say no, I don't use those methods. I typically use "curves" only with my B&W images if I feel the need to adjust tonal ranges. As for the second question, I prefer to scan my B&W film as 24-bit RGB files, and then I'll usually convert them back to grayscale in post. Reason why I do this is because it takes much longer for my Epson 4990 to scan a grayscale image than a color one -- like 3 or 4 times longer. You would think it would be just the opposite. I don't mind though because sometimes I wind up with B&W images with interesting tints to them and I'll end up saving them as color images, just because I like the tints.