It is a very tricky question in my opinion. The "theoretical" throughput of FAS2240 is phenomenal (just short of 2GB/s for sequential reads over NFS), but as they say - your mileage may vary & it is extremely unlikely IMHO you will ever get close to these kind of figures in a real-life implementation (especially when using CIFS).
In general, there are many gotchas: how is configured your CIFS client? what type of network are you using? are volumes fragmented (yes, it does make a difference for sequential reads)?
That being said, FAS2240 sound like a sensible choice in this scenario.