I have a low opinion of achromats, so won't go there.
But to the OP, consider this. If you see a small fringe around a bright star, remeber that most of the blue enegy is still concentrated in the Airy Disk.
In an Achromat it is so defocused that it spreads the energy in a large area around the star. Anyone using a big 6" f/8 achromat will tell you that on a bright star, there is a big purple glow. Now of course that energy came from the star, but imaging how much of it there must be that even though it is so defocused, you can still see it!!!!
Enter the modern ED scope. The level of correction is so much better that often, the only thing visible is a slight fringe. The amount of blue energy still encircled inside the green light Airy Disk (by comparison to the achromat) is huge.
The filter not only removes the fringing around the star, but if it is effective enough to do this in any meaningful way, it also removes a great deal of that same blue energy from inside the green light Airy Disk.
And it does it to every star in the field.
This is the way filters work. They can only remove energy. In the Achromat, the purple in the field is of course bothersome, but it is so diluted that it does little to further damage the image. The contrast loss is due to the energy not being where it is suppsed to be, not where it ends up.
If you use a filter that is strong enough to eliminate the fringe, you also take that same amount of encircled energy that is still contributing to the limiting magnitued performance and take it away. All of the stars in the field suffer the same fate.
I tried to turn a 6" f/8 achromat into something better by using filters, but they were so inferrior to a 6" Mak Newt that I gave up completely.
And the first time I used a 6" ED scope (Meade 152ED) the differnce in performance was pretty staggering. No filter I used on the achromats really did much to improve the detail (though again, a filter can enhance some details, but always at the expensce of others. Think about red and green filters on planets.. Some people love them because they feel that each allows better detection of some specific kinds of details. I am sure a yellow fitler would do the same).