Is this better???

Yes!

Meanwhile, any trouble?

Ha! As I earlier predicted, adding a third layer added an order of magnitude of difficulty. The air turned blue when I lost the RAS pin of one of the middle chips in a stack. Attempts to dig the epoxy on that one hadn't suceeded by the time all the excavation had disturbed the RAS pin on the chip above it to the point where that one disappeared too. At that point I removed and replaced both chips on that stack. Fortunately desoldering the extra chips was easy (so much so that if I had known I would have not bothered digging at all). Added two new chips, wired up the RAS line for the bottom layer and and then noticed that I'd lost the top RAS pin on the other stack that now had a wire running across it (that I had absolutely no desire to remove.)
After turning the air blue again, that one did excavate (easier to excavate the top of the package down). Got the second RAS line wired.

Tested, removed one short and one open pin (not bad considering) to pass the memory test. But it fell over whenever I quit the player app on the serial port or whenever the (huge) database was being loaded, always with the same 'Bad Address' error. Spent an age carefully testing and retouching all the address lines (which aren't exhaustively tested by the kernel) to no avail, same error every time. Finally broke down and rewired the RAS lines at the CPU for 32MB only which passed a soak test. Rewired to use the other 16MB as part of 32MB which also passed a soak test. Paged Mark who spun a kernel fix in a few minutes. (New kernel should work for 64MB too apparently.) Installed kernel, tested fine on 32MB, rewired both RAS wires for 48MB, prayed to the God of Small Things Containing Magic Smoke and booted into 48MB nirvana.

Any ill effects?

Only a few frayed nerves.

Any noticeable differences?

I don't know that I'm qualified to tell. Obviously the player is still only using 16MB, and that is where you will see the biggest improvement when the empeg guys can be persuaded to spin a tweaked player binary sometime, your disks just down spin down.
The web interface is very snappy - I can refresh /proc/empeg_screen.png without any delay.

Any photos???

Not yet. My (old) digital camera doesn't do macro. I'll try and take a couple anyway.