In my opinion the protocol doesn’t make the difference. Both can handle this kind of load, if bandwidth is sufficient. Even the cost will probably not differ too much. Though managing iSCSI is more difficult than managing FCP, not only on installation but also on maintaining. Firmware is changing rapidly on iSCSI where on FCP all kind of possibilities are very mature and sustainable.
The most important part of this kind of infrastructure though is the storage array. It should be capable of handling this kind of load and the requested amount of I/O’s. This is releated to the amount of read and write cache and the complete throughput of the array controllers. So agreeing on the statement that a complete infrastructure for your environment will require some more investigation. But overall I would suggest to run on FCP because of management and robustness.

We just installed an iSCSI array. Don’t worry too much about the numbers. Like MrDenny said, it’s all about disk speed and how much data is going to be cached. Best thing to do is a “Proof Of Concept”. Any SAN vendor worth anything will be happy to bring in multiple arrays and let you do any number of POCs on the hardware. The hardest part is coming up with a test plan to accurately test the equipment.