On the flat and empty, but with its lidded canvas "bag" fitted, it makes me drop 2 or 3 gears. Very fully loaded with driftwood it makes me drop 4 -5 gears. On steeper hills I drop to my crawler gear and sweat like a waterfall. The tyres are rated at 35psi. I immediately took them to 40. It's important esp. with a heavy load to make the trailer nose-heavy. This might occasionally cause the bike's front wheel to want to lift off the road, but that's much better than contending with the annoying and difficult rocking motion which can develop if the load is evenly balanced or heavier at the back.
A cycle path runs along the estuary shoreline where there's a lot of driftwood. It's not so far from home and I can get out and back with a lot of wood in little more than an hour. I take with me a small bow saw and, because I'm only 2 - 3 miles from the city centre, 3 cable bike locks so I can lock the bike to the trailer and both to something else, and then wander away.
Once I'm home any seaweed which comes along with the wood gets put into the compost bin. I use the chainsaw to get the wood down to stove length and because it's nearly all dry I bring some of it straight into the house where for several days it gives off a pleasant, fresh and salty smell.
I imagine the trailer will double as a garden wheelbarrow occasionally.
A bicycle trailer, post manufacture and delivery, and heating with (free) biomass together amounts to some useful carbon footprint shrinkage, I think.