I was thinking about enlarging Ektar 100 on Fuji Crystal Archive paper in my darkroom ,but I was reading on the Kodak site that Ektar is optimized for use with Kodak paper.Will I run into trouble getting the colours right ?
I've enlarged with saunders, leica, and omega from fuji to kodak and vice versa. I wouldn't worry about it, it's more than anything a marketing thing for them to encourage you to get kodak paper. Absolutely stunning results can be made from any combination. It won't make your pictures any less or more vivid with the standard brands from either. So go for fuji because it is cheaper, and looks amazing. and this is coming from a kodak enthusiast.
It looks pretty fantastic on Fuji Crystal Archive; however, it is probably due more to the fact that I had a great set of experienced lab technicians editing in the darkroom.
I remember when people warned not to use Gold 100 with Fuji paper, and they were proven right. The Fuji pictures were muddy in comparison to Kodak prints. I wonder if Ektar 100 may be similar in that respect, but if others have already tried it and say its ok- then maybe there is nothing to worry about. But I would believe if you want optimum results- use Kodak paper.
As PE has stated many times, Kodak designs their color paper to work well with all brands of film. Fuji designs their paper to work best with Fuji films. There is a difference, but still, one can get good images from Kodak negatives on Fuji paper.