I have. I'm getting two of them this week (thanks dougg3!), and a PLCC32 to DIP32 adapter for my burner.

It may be possible, later in the ROM boot process, to use an ethernet card's .Enet driver registered from a decl rom to directly drive a card. Grabbing something over TFTP wouldn't require a very complicated IP stack, retrieve an image to RAM, and then plug in my existing ramdisk driver. Or even better, figure out how to pass it off to the builtin RAM disk driver.

This is somewhat related to my current (slowly ongoing as time allows) project of trying to present a file located on an HTTP server as a block device to Mac OS, and doing ranged gets & puts. Doing the ranged gets & puts is easy using MacTCP, and the block device is easy using my existing ramdisk driver implementation. Making calls to Mac OS libraries from within a driver are problematic, so I'm currently trying to rework my MacTCP accesses around that, and I'll see how it goes. I'm hoping you can just drop a vmac/basilisk ii/sheepshaver disk image on an HTTP server and mount the disk from a physical mac.