No I did not damage the countertop, but as a precaution you may want to put masking tape where the lip of the bowl meets the countertop. Be sure to remove the four(?) bolts holding the bowl to the counter before you begin. Also, be sure to remove all small children first as there will be much cursing.
There is one other improvement I recommend. On this Ericson model, if water leaks into the compartment under the sink, it will run out onto and under the cabin sole. I smeared silicone on all of the seams under the sink to a height of about 4 inches. I then drilled a 3/8" drain hole from the head compartment into this undersink space. You have to drill through the raised fiberglass liner. I was able to get the hole about one inch off the sole. I then inserted a polyethyene tube into the hole, glued it to the inside of the liner, and cut the tube protruding into the head compartment flush with a razor. Now any water getting under the sink (e.g. from overfilling the water tanks if the thruhull is closed) drains into the head compartment and then into the shower drain.
On the subject of faucets, I replaced the crappy Tempo faucet for the cockpit shower with a nice chromed bronze single knob model made by Scandvik. Since only a single hole is required, I first installed a beige 1/4" thick plastic plate to hide the three holes made for the Tempo model.