I installed Martek davits on my 321 a few years ago. The installation was pretty straightforward in terms of layout, drilling, sealing, bolting, etc. I did need to add a pair of reinforcing beams from the stern rail forward to the deck in order to keep the weight of the loaded davits from pulling the stern rail backward. Martek supplied the rails to my length specification, and was easy to work with.
The davits were plenty strong enough to hold up our Zodiac inflatable with a 9.9 hp motor on it.
I traded the boat about a year ago for a Beneteau Oceanis 36 CC and moved the davits from the 321 to it. They are still working fine.