Hello,
I am a painting contractor in NYC and I've been using this (
http://www.wicycle.com/cargo.htm ) trailer since the spring on an almost daily basis. I regularly carry huge loads weaving through traffic over New yorks badly potholed streets without problem. It's a remarkably tough and well designed tool that I can't recomend enough. Towing at speed is no problem either but I would do so with caution with large loads as stopping quickly can be hairy. It breaks down in a heartbeat too so when I get to the job I just whip off the wheels and chain it to a street sign with my bike.
At 18lbs it seems heavy, but when attached to the bike unladen I don't even notice it.
I would have no problem using this to tour but would probably buy the smaller, narrower version.
For day to day stuff use a 35 gallon Rubbermaid storage container.
My trailer carries way over the rated 125lbs without complaint and I have no fear of breaking it.
Good luck.