Yes the ATK 414 is one of the best for low dispersion ripples but sadly one of the worst for high dispersion ripples seen with the LHIRES at the highest resolution (unlike its predecessor the 314 which is good at both low and high dispersion.) Unfortunately none of this is known until one tries to use them for spectroscopy. The low dispersion ripples are all but eliminated by using a flat but the high dispersion ripples can be really tough to remove.
Cheers
Robin