i, personally, would want a higher wattage over my sink....

I have read your question and will do my best to assist you. To start I have a few questions. What is your existing kitchen light levels? Bright, Ok, or Dim. The brighter your kitchen is the less light you will need over the sink. If you are happy with the general lighting levels in your kitchen than I think 50W of light would be adequate. If your kitchen is dim I would recommend installing a light fixture that could accept a 75 watt. The problem is most 3 and 4 inch recessed cans have a max rating of 50watts. You might need to increase the size to 5" before you are able to install a 75watt bulb. My second question is how tall is the ceiling over the sink. If the ceiling is less than 9 ft I would say the 50watt fixture would work. If the ceiling is over 9ft I would recommend using a 75watt fixture. Another recommendation is to install a wide spot or narrow flood bulb into the recessed fixture. (if you have the option) If you install a spot type light bulb it will help direct the light straight down and focus it on the sink area. I hope that this info will Help you with your recessed can light installation.

Here is a link that might be useful: Recessed Can Light