My installer ran two "beams" along the front & back of the sink. They were screwed through the walls of the adjoining cabinets. They're high enough to not be a bother. We did not screw into the countertop.

Same here. My installer did not use the clips that were supplied by Blanco as he claimed that they would eventually rust out.

Any ideas?

there are undermount support systems which will support your sink without the need to screw them into your counter top. They seem to be quite effective with no damage to your counter top and you can change your sink any time you want!

Plywood supports (in my case) or
http://labfixtures.com/epoxy-resin-sinks/undermount-sinks/sink-supports.php

There's a couple of types out there hat are way inexpensive and are 100%
reliable - one from Braxton Bragg and the other from GranQuartz.

here's what one looks like:

{{gwi:1574358}}

hth

kevin