I don't know all that much about it. For example, I do not have one. I have been examining the available information and Apple's publications from the era with an eye to producing a modern alternative. But no one should hold their breath in anticipation. I am not very fast at such projects.
Also, I'm having a bit of preliminary design consternation. The interface to the SE/30 PDS slot seems to require about 97 signal lines. And, I'd like to have about 32 data lines to graphics RAM, and 20 address lines to graphics RAM, plus another ten or so lines to the monitor port(s). This makes about 160 signal lines and the largest, hand solderable FPGAs come up a little short of that.
I can probably work around it, but it would be really nice for the PDS slot interface to use different signal lines from the graphics RAM interface, because one runs at 16 MHz and the other could run at up to 200 MHz.
So, I'm looking at which FPGA developer kit to buy and none of them seems to quite fit the bill. Digilent's Operations Manager tells me they may have something a bit more fitting in late summer...