Some things I didn't mention the first time around:
One downside of the Burley is they even though it has a cover, it's not completely waterproof. I would not be surprised is water could come in through the bottom around the wheels, and I know for a fact that spray from the rear wheel frequently gets thrown under the front flap and into the cargo compartment--even with full coverage fenders.
The push/pull I mentioned definitely seems to come from the tow bar flexing. I loaded it up with 80lbs of cat liter today (and a few small items) and rocked it back and forth, and could definitely se flex. I don't think it's really anything to worry about though, and it's really only noticeable on roads that are crappy and have deep cracks at regular intervals.
The trailer handles just fine with 80lbs of cargo. Definitely slower, and you will pay for any attempts at ast acceleration, but decent top speeds on the flats and high top speeds on the downhills are the norm. Much slower when going uphill, but that's why the Long Hual Trucker has a 26x32 granny gear (though I didn't even need to use the granny ring today, and I don't think I even used the 32 in the back.
Top speed with the trailer today was 26.4, top speed with it loaded was 26, ride length was 12.21 miles.
One thing to be careful of: The trailer rides so smoothly sometimes that it's possible to forget how heavy it is, but it definitely takes a toll on braking. And mounting the bike when facing downhill, it is more vital to clamp down on the brake levers.
That said, I really want to get one of the Rans Hammer Trucks this spring, as shown by Commute by Bike. I was disappointed when I first learned what they aren't compatible with Xtracycle parts, but they also have a much higher cargo capacity, so I guess that's a win. I was never a huge fan of the crank forward bikes before, but this seems like an ideal application. I'll have to go about 30 miles to get to a RANS dealer though to test ride one to see if it works for me. But hey, I think I should be able to get there by bike, so I can score poiunts with myself at least.
Oh, I also forgot to attach the third pic of my trailer shopping trip the other day, it does a bit better job of showing how much it was carrying: