The slide-holder for my Epson Perfection 2400 Photo flat-bed scanner is considerably more robust that that for the Epson V500. I can understand the complaints about the newer holder.
I concluded that an autofeed slide scanner wouldn't save as much time as one might expect. While the scanning might be considerably faster, there would still be the "overhead" of selecting the slides to scan, naming each file containing an image, and arranging the files in named folders / directories. This "administrative" work took much of my time, yet was vital to making it possible to find the desired scanned images in the future. Some of it could be done while the next batch of four slides was being scanned.
Considerable time was also taken when it was obvious that a slide needed exposure, gamma, or color correction after being scanned.