And I'll ad mine to the mix.
I bought my first trailer before my bike. Makes good sense. Just that I saw the trailer for sale before I found the bike. It wasn't until after I bought the bike and installed the towbar that I discovered the trailer never had the rotating coupling. Generally on the road it was ok but a different matter when it came to slow speed U turn's etc. Guess i got used to it after awhile. I sold this trailer a few weeks ago.
In January 2011 I found my current white Classic trailer. It's about twenty years old and has been well looked after. I upgraded the clearance and tail lights to LED and I was lucky enough to find a set of tail lights that matched the original. This trailer is a little larger than my previous black one but it isn't as heavy. I did notice that when I first picked it up it swayed a little when i was over 80kph. I put that down to it being empty and a fairly strong side wind. Tyre air pressure was a little excessive so I fixed that back to the recommended 12-15psi. It's been stable ever since.
The trailer has an interior light but until I rewire the bike I have moved the wire to the tail light connection. Also looking at installing a 12volt battery and possibly solar/bike charging system.
Under normal riding conditions the trailer is hardly noticable. Maybe the odd downshift when passing or up a hill otherwise 5th gear all the way from 60kph. Most of the time unless I have my partner on I double shift and go from 2nd to 4th with out any apparent complaints from the motor.
Nearly forgot. My average fuel usage when towing at 90kph gives about 400kms before the fuel light comes on.
Alan