We just got back, after two nights and nearly 3 days away in our 4m.
And there I was eyeing up all the Schmidt and Zwerver polycotton beauties that the Dutch contingent had brought, from ours!!! 
I think half the Netherlands had camped where we went. And they know how to do it properly, but not one of them had a bell tent.
Anyway what I would suggest uis the worst thing about them, is the drying time. I went round bashing the walls this morning but they are still very wet - it's not 'weathered' yet, but it poured yesterday and we didn't have any leaks worth a mention, about 5 random tiny drops from the ceiling I think this morning and it was totally lovely.
BUT we had to clear out by 11 so I bundled it into the car quite early, and then had to put it up again as soon as we got back. It is now half up in the garden (pole, some pegs, ahem, not properly as we haven't the space)
I am hoping it brightens up today, it's certainly windy.
It was WONDERFUL having such a lot of head room. That was the best thing, and my 10yo and 6yo and 6mo didn't seem to have any problems with sharing the space. It was totally big enough - we couldn't go out most of the full day we were there, and just sat in the tent, except when ds1 decided to go swimming and it wasn't cramped at all.
Ours was the highest ceiling by a long way and to me being 5ft7 that makes a lot of difference to how much I enjoy it and how much I get the urge to come home, iykwim. I didn't at all really and normally I am keen to get back here.
TIY I think you're quite tall (we've met once - rabbits!) so this might be something you want to consider as a factor.
I couldn't reach the top of the pole inside ours - think it's 2.5m? and the 5m one is even taller.