Hixxy, the Yamaha 85s are based on the same block as the 90 and have been around longer than Johnny Fuller. Simple in design and have a proven track record both for leasure, commerical and racing. We have one in the dive club. It was used by a former dive school before we got out hands on it. Despite not being servied for a decade with a little TLC she now runs well and is proving a good buy even if she is 15 years old.
But note it will be premix so stike a hard bargin with Atlantic if you go and look at her.
We use 5 - 6 gals an hour with 4 divers and kit cruising at 22 knots.
Merc props will fit with a conversion ring and are half the price of a Yam prop.
The Avon is a great hull too, to only down side is the seat is a little low for some although there is a feeling of sitting in rather than on the boat.