Take a look at the sustained transfer rate, and see if one of the bigger drives may suit your needs a little better.
You are giving up quite a bit of space for a 10-15MB/sec increase in mechanical transfer rate -- and most all drives will transfer at the same rate when the data is in the cache.
If you really need the speed a RAID may work better, all depends on how critical that extra bit of speed is, the seek time, and/or how well the cache is tuned to your specific use (the cache tuning can may or break you.)