> contrasty and underexposed slides. can i get by with LS-40 as i don't make
> big prints or do i need to buy LS-4000.what is the difference?
The main differences are (AFAIK):
1) LS40 is 2900ppi and the LS4000 is 4000ppi
2) The LS4000 can do single pass multiscanning while the LS40 cannot.
I can't remember if the LS4000 is advertised with a greater dynamic range?
Single pass multiscanning will certainly help with dark slides.
Check how the Nikons compare pricewise with the SS4000. Personally
I find ICE indispensible but I also understand that other scanners like the
Polaroid show less dust and scratches than the Nikon scanners so less
spotting is required anyway.