The more expensive brands you see are analogous to L vs non-L glass; both do the same thing, one just does it better, the question of course being how much better and how much does it matter? The critical issue with filters is the coating applied to the glass element. Lower quality filters will not transmit light as cleanly as a premium one will, however you would really have to ask to test the filters yourself to see if the difference is worth the extra $. Most making a living by photography would err on the side of quality, however I suspect that you'll find the difference to be negligible. More expensive filters may be less prone to artefacts lens flare, but considering you can use unexposed film as an IR filter with acceptable results the difference you'll see between the two coatings won't be too obvious. edit: 1st post ftw