Many years ago I purchased the Nikon Coolscan V and never regretted it. But, I ditched Nikon's software and bought VueScan's professional software that runs on my Epson flatbed too.
Coolscan has batch processing capability (feeder sold separately) and I let it run overnight; I thus scanned over 25 000 slides.
Because I don't have the highest dpi model, my blue skies are a little grainy; I use Aperture's skin smoothing brushes to clean that up. The results are great. You should look up on eBay to see if there are any on sale.