Hi,I currently have 2x 4mtr sea riders.One with blocked hull one without.One has 55hp engine other 40hp.Personally I have found the following.When launching/recovering on a shallow slip,beach etc.If the hull is blocked then the trailer doesnt have to be put so far into the water for recovery as its much higher in the water & can come closer in when recovering.If like me you are mostly in a wetsuit when launching/recovering then this is not so much a problem.
The main advantages for blocking the hull are the fact that the transom top is very close to the water with the weight of a 40 or 50hp outboard.I found I would take in a lot of water sloshing over the back when the hull was flooded.If its a little rough then you will have the revs down & find the hull floods a bit which sits the baot lower down result...more water in the boat.The fact that Avon dont do a flooding hull anymore speaks volumes.