The two brands that I have found for music are Mobil Fidelity Sound Labs (of course) and Quantegy. The Quantegy discs add a special scratch resitant layer. Has anyone tried the Quantegy discs? I want to make sure that extra layer doesn't cause longevity issues.

Layer of what? Various manufacturers paint a harder than average coating over the label surface; it seems questionable that it should really be considered 'extra' or that it is extra thick. It is highly improbable that there is anything 'extra' on the playing side. Any additional coating on the label side, such as the solid white surface for ink jet printers that is widely available, probably adds some additional protection against scratching.

I'm sure MF does not manufacture their own disks and there is an excellent probability that this Quantegy does not either. Mitsui (now MAM-A) has always had an extra hard surface they call "diamond coat."

I went back to MFSL's web site and they both claim to be scratch resistant. Here's MFSL's blurb

"...have dramatically enhanced resistance to light and heat. Additional features include instantaneous pit burning (burst burning) for superior pit formation and extremely low to no error rate; and an added, patented, scratch resistant, protective surface."

They are probably both getting them from that company you mentioned, if I were to take a guess. MFSL sells their discs cheaper.

IIRC, the MFSL discs are made by Mitsui.

Damn, are they still around?

http://www.cddimensions.com/cd-r_media/mitsui-cdr-media.asp

The same Mitsui that all went dead in two years and a half in my collection ?
In the exact same storage conditions, Verbatim Metal Azo have survived 6 years with no problem.

EDIT : if they are gold, this is another matter. Gold CDRs have nearly all survived here, while silver CDRs from the same manufacurer, burned the same week and stored together are all dead.
When I say "all", in fact, it is about 3 gold CDR vs 30 silver ones.

Who know how to account for things. Some published testing I saw several years ago rated Mitsui at the top for quality and durability. I've used three to four hundred Mitsui disks over the past four years, not one of which has ever given a problem. I recently got a Lite-On CR-RW drive just so I could use K2Probe. The first few disks I ever wrote, in April of 2002, came out with very low error rates. On the other hand, I've gotten really rotten durability out of a batch of PNY brand disks I purchased right before starting to use the Mitsui. Both have been stored under the same conditions.

I've never tried the gold ones. They are about 50% more expensive and don't seem to offer anything more for me.

I have tried those MFSL CD-Rs, they are indeed by Mitsui. Here is the review.