"John Greenwood" wrote
| I was going to use a downcut blade and I assumed the sink lip would be
wide
| enough to hide any chipped laminate.

It probably would be, but the distance between the cut line and the wall or
front edge of the worktop might not be enough to allow free clearance for
the jigsaw body or adequate support. You might get 3/4rs of the way round
and find the jigsaw hits the wall and you're stuck.

Owain