Is an FPGA the Best Option for High I/O (120-150 Input) Prototype?

For some reason I have posted a number of replies and they are not coming through... If only my other posts came through the context of the system would be more obvious. I am assuming they have been moderated for some reason.

I would like to thank everyone for their advice. I have since investigated the CAN bus approach but since it is a prototype and I will get it "professionally" designed I am going to go with the microcontroller based approach with a chain of 8 MCP23017 components which gives me 128 I/O's. I have done some quick calculations in regards to how often I need to process the loop and I am within the required timings so I will not miss any critical events. Noise will not be a concern at this stage from other electrical equipment (but my prototype will validate this).

I am a lot more comfortable with this approach now that I have somewhat "validated" what I am trying to do and heard about some other options. Once again, thanks for your help... I'll need to find another use for my FPGA for a future project.