In the past, if, for example, I wanted an electrician to check something out, I could just tell him...
Having been on both on a can and in a slip, the first thing I'd say is the boat got a lot more use in the slip. It was there, ready to go at any time.
1. The frig was always cold, often with drinks and sometimes food already in it Ice stayed frozen in the freezer.
2. The batteries were always charged
3. Great water pressure w/o running the pumps or draining the water tank
4. The slip made loading and unloading very easy
5. We never did overnights on the can but often did in the slip.
6. I no longer had to row out to the can (one time the wind was blowing so hard I gave up) and then try to find someplace to dock the boat to load guests and provisions
7. We worried a lot less about the boat being damaged. Boats tend to lose their mooring a lot easier on a can. One time I was lucky enough to be on the boat when a loose boat came our way. We managed to stop it then towed it to the nearest can. I often wondered how the owner found it.
There's more, but for me, if there's a choice, I'll take the slip any day.