I recently had a fair bit of leisure time on an Oyster 65.
The skipper always works on Oysters and knows them pretty well.
One thing he mentioned to me that I did not know was the interior
can be expensive or comparartiuvly cheap
that particular Oyster was one of the cheaper fitouts. The cabinetry in the heads was about the standard of my Benteau saloon
cabinets. i.e nothing too flash.
The dining table was matt, not inlaid etc... the owers didn't mind that as they always use table cloths anyway.
So you may want to have a close look and see what the fit out is like and value it accordinly.
I love Oysters. Fine boats. I haven't been on a Hylas so can't compare... but the Hylas ads in Cruising World always seem to be the same, but Oyset always seems to be bringing out enhanced models.