Glen
we bought one and it was quite slack the first couple of times and did blow about a bit at first, but gave us loads of room. We improved the slackness by using the storm straps provided and this has stood up to some fairly windy conditions. Although you can leave it in the awning channel, we prefer to remove it when travelling - only takes a few seconds.
We also have a Scenic+ which is a much tighter fit, but less room. The Scenic poles can mark the side of the 'van, but we use rubber 'feet' which helps.
Depends on the room you want - our dog sleeps in the awning and its also a storeroom for often wet outdoor clothes. On balance, the Scenic+ is our choice for most of the year as it is also easier to put away when wet - we just roll it up, store in the shower, then peg it out when we get home.
Hope this helps.