captain It's a hard one. I really like both the mosey and the versa. I just have the standard one not the gt and it copes fine on uneven ground, rough grass, cobbles etc. The reason I got the versa was for exactly the same reasons as you and because the bee can't handle that sort of terrain. The fold on the versa is amazing, it's so compact and flat. (photo in the car boot) As you can see it is quite a bit shorter than the mosey.
However I do find it heavy to lift in and out of the car. I normally keep the bee in the car and leave the versa in the garage and wheel it out when going on walks or use it for days out as the basket is massive. I also struggle a bit trying to fold it as you have to pull up the handle under the seat, it normally takes me a couple of attempts. The versa is nice to push though and doesn't feel heavy and is easy to manage one handed even going up a pavement hill.
I've not used the mosey outside as I'm still trying to decide whether to keep it. There are good reviews of the easywalker mini and june buggies so I'm assuming it's similar to them in regards to pushing. It's lighter than the versa and narrower which is good and it also has the lie flat seat which is a plus for me, I do prefer them to bucket seats. I like the fact that the hood is huge and the back chassis bar is raised up so you won't kick it when walking. I do prefer the handbrake on the versa over the mosey footbrake.
As I said in post above, the only downside for me is the folded length. It is still compact compared to other pushchairs I've had and a big advantage like the versa is being able to fold in one piece in both directions. My 3 year old also fits in both pushchairs fine with room to spare so they would both last long term.
They are both really nice and I think you would be happy with either of them. The mosey probably wins as it is more compact all round and lighter and I could (maybe) sacrifice the fold on the versa. I would definitely measure your car boot though to make sure the mosey fits.
Hope that helps, feel free to send me a private message if you have any other questions or want photos.