I asked a similar question a year or so ago and consequently started wearing my running shoes out on Dartmoor in the summer. I have to say the wet feet problem (and the smell) is something that I couldnt get on with personally. My boots are actually very comfortable, my feet dont hurt at all, nor am I especially glad to get them off other than to get a bit of air to my feet! The running shoes were nicer of course, but not once wet!
I can definitely see the benefits of hiking shoes for warmer or drier climates though, they would be ideal for hiking in Iceland I think, but I'm not sold on the idea for the UK on a multiday basis.
Having set it up again last night in the park it’s pretty clear that with a low pitch I almost have to sleep with either my head or toes at the door. Although I would fit at the far end as well I the ‘ceiling’ is just an inch or so above my head and toes.
Knowing the places that I tend to pitch I think people make a very good point about the lack of flexibility of an inner/floor. For the time being I think I will go down the floor and bivi route and see how I get on.
Groundsheet wise I’ll get a bit of Polycron to get started but I might make something out of silnylon eventually.
Are there any good pre-existing bivis that I should be looking at for my height? I’m thinking that it’s particularly important that the footbox is waterproof given that I am probably going to have my feet at the door.
Thanks so much for the comments, this has given me a great deal of help!