If I'm not mistaken, with the FPGA itself you can do quite a bit of fancy action-reaction or even PID loops
ADC / encoder -> FPGA ->PWM
How configurable the cRIO is I'm not sure, being here in Singapore the chances of getting my hands on a cRIO isn't very high. Yet.
Found a useful image here:
And here
One should offload most of the closed loop logic into the FPGA while the RTP handles monitoring, higher level processing, scheduling etc. Perhaps this explains why there are no support for interrupts. You don't need them! I think there is a certain level of paradigm shift from PIC based microcontroller programming to the cRIO observed here.
In my opinion, having an embedded computer in a ruggedized chassis at $1k is pretty decent. Apart from their development costs, one must remember that these are industrial grade equipment. Maybe within the range of other industrial PLD/CPLD devices.
On the sidenote, may want to consider thinking how many IFI processors, OI, etc which are already fried (dead), due to mistakes in connection such as polarity (oops!), high current surges, etc. I think the cRIO would be more reliable in this sense too.
Edit: I'm thinking of sampling a cRIO here in SG, and probably budget for it so that the kids here who were playing with vex can try out some new stuff, though I'm completely clueless how to go about doing that. Any non-FRC members have any idea?