Like Niknak says, I can be swayed by the pros and cons for both systems.
The recent tour I did was not technical but a mostly off road on tracks. My bike had an extrawheel trailer, the other half had ortlieb panniers on the back.
Handling wise the trailer has a less noticeable effect than the panniers when you first get on, but you soon get used to the handling effects with either system. The extrawheel will follow wherever, down bumps, up kerbs etc.
We never had to lift over anything, but unhitching my trailer and lifting it over seperately would have been easier than lifting the other bike with fully loaded panniers.
I'd say with my trailer you can't really put any more weight in it than panniers (well you can but I wouldn't want to) but things like thermarests and sleeping bags which are bulky but light don't end up using half your space.
Three rear wheel punctures on the bike with panniers, but prob not really significant as that bike had an extra 5 stone of person on it too.
Transport is where trailers can be more difficult, my trailer is only size of a wheel though so not an issue for me, can lift it with one hand. Wheeling bike along with trailer attached is fine, only an issue when it comes to reversing.