So after looking at the Virtex4 line of devices and their associated features
First of all, suppose I'm planning on filling an FPGA full of logic. I'm probably going to run the majority of that logic in the same clock domain so I don't need a whole lot of DCMs. However, I do need some way to get my data to/from the chip. What's up with zero transceivers on the "logic platform"? The same can be asked of the "signal processing platform". I was so looking forward to getting away from the old parallel I/O issues, and if I'm going to have to deal with that, maybe we better leave those DCMs on there. It wouldn't take very many transceivers to alleviate the issue.
Second, what about those of us who build and prototype digital bus controllers, routers, and similar applications. In that situation I'm looking for an FPGA with lots of memory, lots of transceivers, lots of DCMs, a fair amount of logic, and not much else. DSP and Processors don't really help me in that type of application, yet to get what I need I will end up spending the extra money for the FX chip.