Hey Dazza,
Having a Trackabout, you can guess what I'm going to suggest
. I dropped our camper into a creek at Easter, and landed the whole weight of it on the number plate support panel. It's dented (as you'd expect, but with a bit of 'readjustment' it'll be good as new again. If I can't break it, then it must be bombproof.
As has been noted already, the canvas on the Trackabouts is fantastic. I can have ours up and down by myself in no time.
That said, I do like the Jimboomba gear a lot. They're well built, they're well thought out, and they make a lot of sense. The canvas is very well regarded. Speak to Jimboomba owners, and they're much the same as Trackabout owners.
Personally, while I like the idea of low weight and no rust, two things concern me. Firstly, my personal thinking is that the dry weight of the bare trailer probably doesn't matter as much as you'd think once the heavy gear (canvas, water tanks, toolboxes, all the crap we take along, etc) is added in. Secondly, repairs to aluminium isn't as easy or as available as simply welding steel. True or not, they're the main points that swayed me from a Jimboomba and onto a Trackabout.
Good luck with a difficult decision!
Cheers!
Matto