highly-parallel highspeed connection between two FPGA boards

Hello,

designing a motherboard featuring a Virtex-4 FX140 FPGA with 24 integrated RocketIOs (Gigabit SerDes IOs) I am now facing the problem of how to get the signals off the board in a most space-saving and elegant way?

All 24 differential signals will be connected to some DACs outside the motherboard to convert the signals into the analog signal domain.

In the definition of the interface I have nearly all effective degrees of freedom. I once learned that coaxial connections are the most appropriate way to do so in terms of signal integrity, but with 24 differential signals and bidirectional connections that would mean at least 96 SMA connectors (that takes very large board space and implies some skew problems due to the differences in the line lengths).

I once used the Tyco ZDOK system (plug + receptacle) for board-to-board connections with up to 80 parallel signals but unfortunately the performance was not satisfactory, so I won't be using them again. Are there any other interface systems for the above described purpose or ways to build a highly-parallel highspeed connection between two boards?

I appreciate every kind of suggestion and help. Thanks a lot in advance.

Regards, Maurice