Jack, is BGA technology out of the question for the FPGA? If you could manage the CSG225 package, it is only $1 more than the TQFP option (digikey, unit 1), and would offer the possibility of having an LX16 option as well as LX9. If it is possible to route to some of the extra I/Os, you could stick with the x16 SRAM and not make any compromise there. If you could mange a CSG324 BGA, then LX9, LX16, LX25, LX45 are all possible. That would be great, even if most of the extra I/Os are not routed out. I realize that inspection of BGA soldering is probably an even bigger issue than the routing of it. At least with the routing, it is a one time problem and you know where you stand. Overall, I think SRAM is a lot more approachable than SDRAM design. On the other hand, some of the xilinx parts have integrated SDRAM controllers, paying attention to the routing and connecting the SDRAM to the right pins and making sure all the right traces have matching length, you get speed and capacity without too much pain.