Does size make a difference

Hi.
Currently looking at getting an auto-sleeper, torn between a Winchcombe or Bourton.
Does the difference in size make much difference. It's just less than a metre. I've previously towed a caravan, and had motorhome experience in a rental a couple of times but smaller than either the two above

It's not the size that matters - it's what you do with it. Or in this case, what you intend to do with it.

If you only ever intend to drive on major roads and to travel to medium-to-large sites then the difference in size probably won't make a difference, but on smaller roads and more confined spaces, a 6.5m long vehicle may be enough of a handful, compared to the alternative of a 7.3m long van which is 120mm wider?

Will you completely fill the storage in a Winchcombe? If so, a Bourton probably won't be big enough. Do you expect to have lots of people on board? Then the extra floor space will probably be useful.

In summary: it's very unlikely that anyone here can answer your question, because as far as I know, nobody else here knows how you intend to use your van. My recommendation would be to go to a dealer that has both models in stock (or very similar models in terms of size and layout) and try to visualise how you will use the space.

My personal reaction is that "only" just less than a metre extra length is going to feel colossal when you're actually inside one. It's also likely to seem like a lot when you're trying to reverse one!

We currently have a Worcester which is the same size and exact layout as the Winchcombe, our previous van was an Autocruise, the same layout and size as the Bourton. 
The length makes very little difference to me, both are that bit too big to fit in a single parking spot but most places I manage to find a verge to overhang so it is no real issue. In any event you are well used to towing a caravan so I wouldn't worry on that score.
The Winchcombe is a wide van, almost five inches wider than the Bourton which puts it in the league of big A class vehicles like the Morello Palace Liner! (2500mm). That is a noticeable difference so you have to be a little more careful pushing through the gaps. We live in Cornwall not renowned for its wide roads and I have never had a problem in 10 years of ownership, you just get used to it.
The big difference is in the level of comfort, especially with the massive bathroom and shower in the Winchcombe and whilst I believe the front lounges are the same length the Winchcombe feels much bigger inside. We have never succeeded in filling the payload of our Worcester (3880kgs) and I believe the new Winchcombe has even more payload.
Of course you need a C1 to drive the Winchcombe whereas you don't for the Bourton so that may eventually be a consideration.
If I lost my C1 then the Bourton is the van I would buy, the Worcester ( Winchcombe) is so wonderfully comfortable though with the extra feeling of space that I can think of no other reason to part with ours.
So many things might effect your decision but hope that helps a little.
Good luck whatever you choose.