I had a similar quandary, needing an easy, portable and safe way to keep irreplaceable data from on site recording until I got it back to the office. I decided to go with a 2.5" raid system. It is as follows:
Addonics 2.5" RAID System (Selectable Raid 0 or 1) (http://www.addonics.com/products/enclosures/AE25RDESU.asp)
It is USB and eSata (For Optimum Speed), Made out of aluminum for stability, Mac/Windows/Linux compatible and has push-button ejection of the drives for easy change out. It can even (depending on the drives and the USB port) be powered completely via USB. I went with the Western Digital Scorpio 320GB drives (http://www.newegg.com/Product/Product.aspx?Item=N82E16822136197) which have been rock-solid. The whole system, enclosure, 2 320GB drives and cables can be had for under $300.