Porta Bote

we've had a 12 ft one since the early 80's, bought it s/hand with a sail kit.
Usually use a 4hp tohatsu o/board on the back.
As you say great for travelling (we've had a couple of tinnies too) as it sits up on the roofrack most of the time. We've used it all over the top end, Kimberleys, coopers creek in flood (did a shear pin just near the dig tree years ago when we hit a rock).
We've had it outside in the ocean a few times too and it is quite stable, just flexs a lot as the waves roll under. We've been sailing in it too, mostly on lakes.
The biggest drawback is the motor size restriction as the little motors cannot compete with the tides up the top end both in the rivers and the sea.
We also carried it into Twin falls in Kakadu and used it to ferry a group of small kids up the gorge.
The seats, motor mount and the outboard take up a bit of space but can be bagged and put on the roof as well. We've never taken the sail kit outback just used it locally.

We also have the 12ft and a 4hp tohatsu - 14ft is too heavy, 10ft too small.
We continue to use it so that's our testimonal. Wouldn't get a tinnie again , too much wind drag on the roof - the PB is really the thing to have when travelling, it's easy to carry and you've got a boat when you need it. Must say it can be a pain to put on and off roof rack, we carry on top of the camper. Outboard also on camper.

Does the job very well and is easy to assemble after a few goes - don't get the sunshade or oars it comes with - buy from a boat shop. You can also get the dolly wheels cheaper from the boat shop.

Very tough, as they say, and stable. As said, pack the seats etc in a custom bag and throw on roof. You'll need a small anchor too.

Then just add water. :)
cheers
John