I've used a couple of the Zodiac Yachtline versions (380 &420), they have a similar deck and identical hull to the Avon.
They are a really nice boat and for a pootle around the lakes or inshore in calm conditions they are great, smooth dry ride, comfortable seats and lots of storage. But, the moment it gets a bit rough, they loose their appeal. The bench seats are impossible to brace on, water starts coming over the bow and they slam for fun if you try and keep the speed up.
The hull is simply too flat, great for internal space, but terrible for handling waves.
Although there are lots of the Avon Adventure's around, the Delux versions are like hens teeth. You will probably have more success looking for a Zodiac version like
ZODIAC 420DL YACHTLINE / EVINRUDE 50HP ETEC RIB BOAT | eBay
Its nothing to do with me, but thats not a bad price.