If you plan to haul heavy stuff, such as grocery shopping items, the Bob may be better, but for normal touring 45 pounds should be enough (you can put more in panniers if needed).
Nashbar has a friendly return policy, so you could buy the Nashbar trailer, inspect it, and return it if unsatisfied for the cost of return shipping (for a short time Nashbar has free shipping to customer if price over $50). Given the price and the current free shipping, I would give it go.
One other thought, comparing these two, is the availability of spare parts (e.g., skewers) in case that is needed.
Another option, for $200 (and with waterproof bag), is this trailer, which folds:
http://www.actionbent.com/twtrailer.html
Here are few links that may offer ideas (maybe send PM to those on this forum who own it, ask their feedback):
http://visforvoltage.org/forum/bicyc...-pedelecs/1884
http://www.bikeforums.net/showthread.php?t=284119
http://www.bikeforums.net/showthread.php?t=326138
http://www.bikeforums.net/showthread.php?t=378187
http://www.bikeforums.net/showthread.php?t=231665