CMC Magnetics & Verbatim is picking up the slack.
That's a 52x CMC disc pictured above, burned at 52x.
The disc came with my 52x Lite On drive.
I'm getting similar results with 48x Verbatims @ 52x.
Ian reported this week that Verbatim is making 52x discs, but they're not available yet.
So, when Maxell starts to loose market share, they'll start making 52x discs.