TS, I agree with you about getting OEM filters at the lowest cost is the best.
However, I thought it a bit misleading to suggest that tests of filters that are (1) constructed quite differently, and (2) are of different size, would be directly transferrable to the correct filter.
BTW, when I ordered filters from VWparts as suggested above, I got Mann filters. They don't look different in construction from the Purolator/Hengst. Factoring in the shipping charges, it was a wash on the cost vs. buying local. In the future, I guess I'll go to a VW dealer, or other place, and see what I'm getting first.