Hi Paul,
We own a Parker 285 HS Blythe Spirit and keep her on a drying pontoon berth at Thornham Marina Chichester. To date we have had no problems with mud, debris etc in the keel box. We keep 30 cm of keel down all the time she dries out onto a soft mud bottom. Years ago we owned a Parker 21 Cloud 9 and regularly dried out on a variety of sea beds.Again never a problem!There is also a Parker 235 opposite us on a mud drying mooring again, no drying issues. We are converts to the lifting keel concept and the Parker range of boats.Before we bought our 285 we looked at Southerlys,Gibsea, Jeanneaus and Beneteau boats between 28 to 34 foot.All lifting keels. The Parker got our vote! The 275 is a great boat! Find yourself a good one!
David