We sold our 1979 36t, hull #3 last summer and purchased a cs40. We bought the 36 from the original owner in the late 90's. I had helped him for many years prior taking care of the boat and sailing. He was in his 80's.
We loved the boat, spent extended time vacationing and living aboard in the summer. I would trust the boat in any conditions. We had a tall rig and deep keel and we regurally walked away from almost any other comprable boat.
The companyonway ladder is steep but you'll get used to it.
As far as engine access goes when the steps are out and the side pannels are removed you can get at everything. My only complaints were getting to the raw water pump was a pain if you had to do it quick and the vdrive makes access to the stuffing box difficult.
One thing I noticed and liked right away on the 40 is the head is on the port side and you don't have to go around the table to get to it. I never looked at a 36 merlin but the layout looks like the 40. If the head is on the port side life in the cabin will be easier if your stuck below on a rainy day w/ guests.