I own Noritsu ls1100 it’s similar to ls600 but slightly faster. These machines are masterpieces of scanning! I’ve scanned on flatbed epsons and Nikon coolscan iv and it’s nightmare compared to Noritsu. If you have a chance to get one in good condition for a good price (~1000$) - don’t hesitate, get it! Yes, it takes a lot of room, but it’s a professional thing with excellent scan quality. If you have any questions, feel free to ask me))
I have a Frontier SP-500 for over a year now. It’s fast and delivers but the Noritsu gives better, more print like colors and less aggressive sharpening. Together with another member we ran B&W, color negs and Soldes through both to compare. Slides don’t work well on either one of them.
Pakon is another very good option. Performance very similar to Noritsu.