We decided to stick with the Pendragon version 5.1 due to skepticism over stable internet connection in rural Tanzania (although as pointed out in a comment below, it may require a 3G for syncing). The hardware choice was the Dell Axim x51. It is entirely possible that we may have ordered the last five new Dell Axims that exist. To save money and not purchase a rugged PDA with built-in GPS, we went with a separate hand-held GPS receiver, which should be able to communicate with the PDA. It does seem that great organizations like IPA (whom I thank for advice) are switching over to android devices. But not wanting to be an early adapter when my dissertation is at stake, I opted for the older-school technology.
The minor problem is that I left the states for Tanzania just yesterday and the PDAs were still somewhere in the USPS system. Probably the first of many adventurous set backs, but on the bright side, I will have three weeks of programming time with Pendragon before my PI arrives with hardware in hand.
Thanks for all the advice, friends! If you've used some other type of hardware and have a recommendation, feel free to share.