Oh, the same comments on this.
Both Newzbin AND Nzbmatrix are pay sites, the only difference is that just exactly how much 'access' you get my paying, or not.
But really, even Newzbin costs are so low, you pay what, one can of Coke per MONTH for full access? And Nzbmatrix is a $10/one shot? Oh, the burden is cracking my wallet!
Yes, you can find pretty much find exactly (in fact, probably more since they use automated collection) on the other sites (like Binsearch and such), but if you're searching for something pretty specific (like FLAC), it's just as good to spend a bit of time maybe d/l'ing the headers in such groups as a.b.ss.lossless, etc. That's what I find on getting movies, the 10 or so groups I monitor I find 'jewels' that the indexing sites routinely miss.
Lately I've been scouring for FLAC myself, but haven't come to any real conclusion, as Newzbin has amply filled my d/l'ing bandwidth.
I don't know what you mean by 'BDR'... maybe you meant BRD as in Blu-Ray disc? But the same would apply to that. I think that whether it is a site that manually filters, auto-filters, or a combination, I've found over the years they all tend to miss stuff. So again, I'm 'old school' and do headers on selected groups.
You may find after a bit that you'll do the same after you figure what groups has the stuff you're looking for, and you find that idexing sites a/b/c/d missed something that site e somehow found. Or the reverse. Theres nothing like that computer sitting on your shoulders.
And oh, I forgot about something I was reminded of just now; FLAC isn't the only lossless format out there, APE was very popular a couple of years ago (was promoted by 'MediaMonkey'), and there is Apple Lossless, among others. There are converter programs that will change most of them into FLAC.