Esteem re upholstered my Whaler a few years ago. They did a great job but hadn't heard of closed cell high density foam at the time!? I'm sure it's different now.
Also another vote for Pete Sanders. Has made covers of all shapes and sizes for me over the years, not to mention a few sails! Always listens, top quality workmanship/materials.
Can't vouch for upholstery but if it's as good as everything else, you're onto a winner.
Give Kenna a ring and go from there.