Touring Equipment

I have no experience with any of this whatsoever. My only advice is to get lithium ion batteries.

http://answers.yahoo.com/question/index?qid=20080504170740AAevnfI

energy, electricity, power, choice: life.

i want to be able to chart my entire 7+ day tour on GPS. my touring build has a dynamo front hub. i want to take advantage of this rather than use a solar charger like this or a powermonkey extreme.

i don't care if i charge while the GPS is in use, or when not in use.

the PedalPower Super-i-Cable looks like it will do the job, as detailed here. as would the universally praised Busch & Muller E-Werk. however both cost a bomb (the same as/ more than the powermonkey extreme).

a similar, cheaper product is the BioLogic ReeCharge Power Pack combined with the ReeCharge Dynamo Kit. however reviews are mixed.

the BioLogic website helpfully details that the ReeCharge Power Pack requires "Input current: Less than 1A and 5V max".
the hub i have, Shimano DH-3N80, outputs at 6V. which suggests they would be incompatible when used together. hence the ReeCharge Dynamo Kit.

the ReeCharge Dynamo Kit is $30. the ReeCharge Power Pack is $100 and provides 1600mAh.
all of the devices mentioned above use lithium polymer batteries.
is there any reason why i couldn't use something like this PowerGen External Battery which provided 5200mAh?
like the ReeCharge Power Pack, it requires "Input: DC 5V / 1000mA": exactly the same.

does anyone use a dynamo, or any of the mentioned products?