Don't know if this will help, since you're doing a full-piece front -- our sink cab was a recycled wall oven cabinet, so we had to piece it together in any case. This meant that we had more than one chance if we screwed up any of the sink cuts. Worst comes to worst, do it in pieces...?

You could also add a drip rail like we did along the bottom and spare the angst over that particular cut at least; our Whitehaus sink is perfectly flat so we didn't need to hide anything with the rail, but could have if necessary.

Here's what we did, using a jigsaw with an extra-fine wood blade (Bosch makes some nice ones that help prevent tear-out -- I definitely wouldn't use a sawzall!):

It's amazing but you can't even see the seams:

No Sawzall. That's worse than a jigsaw for chatter. Use a multi-tool. A Fein Multi-Master or one of the many knockoffs. If you don't own one, it's time to buy. And create several templates of the panel you will need to cut out from Masonite or MDF and practice doing the cutting. It's better to gain experience on throwaways than on the real thing.

Oh, PS: regarding simple straight cuts with your jigsaw, use a clamp edge or (cheaper) 2 straight boards clamped tightly on each side of the cut, leaving exactly enough room for the jigsaw between them. This might actually be preferable since jigsaws are notoriously shaky. But do what you're most comfortable with. And go slowly but firmly. :-)

Like mentioned, sawzall (reciprocating saw) is not even in the running. They are best for demo work, not a finishing saw.

Jigsaws come in an amazingly wide variety of performance, and I would not use a craftsman on anything where the edge matters, but I've been amazed at how the Bosch does, and I've seen the Festool and that one is truly amazing, but it has an amazing price too. And the blade makes a huge difference, expect to pay about $3-5 for a good blade. Don't cheap out on the blade - Bosch are good.

I owe a Fien multi-tool, and I'm not sure that would be your best bet in this case. I'd be leaning towards a Japanese pull saw and do it very carefully by hand, but that won't work unless you have a straight edge.

DH and I are profecient with all the tools mentioned, and still do a lot of practice cuts to make sure we're going to end up with what we want. And lots of times it takes more than one tool to get the perfect cut, don't try to get into a tight corner with a jig saw - finish up with a good pull hand saw. BTW- most hand saws at big box hardware stores are horrid for delicate work.

I'd also hesitate to use the MultiMaster - I've never been able to get really consistent straight cuts with it because of its size, and it does take forever to cut thicker pieces of wood, leaving more time to jiggle.

I've got the Bosch barrel-grip jigsaw and really like it for fine cuts (although I'm a real sucker for Festool whenever I can afford it, which is seldom).

Let us know how it goes!

Hi,
You could make a template from 1/4" masonite using a jigsaw, fine tune the fit with coarse sandpaper until you had a perfect simulacrum of the sink's profile at the point that it meets the faceframe, then transfer the pattern to the cabinet and use a jigsaw to cut out the bulk of the material, staying well inside the final line. Then fasten the template to the faceframe and use a pattern-following router bit to bring the cut into conformity with the template. Unless you're a woodworking wizard, it it the only way to attain perfection for this cut.
I was able to scribe my faceframe to my sink only because it (the FF) was not yet attached to the cabinet box, and I could manipulate it by itself instead of the heavy unwieldy sink.
Casey

I find scribing a panel much easier with a multi tool than a jigsaw on a vertical surface already in place. You can "carve" with it at an angle to bevel the cut a bit so you can carefully shave off to the exact line by hand with a rasp and get an absolutely perfect fit. A jigsaw is better on a horizontal clamped surface. But choose the tool that you are the most comfortable and proficient with. It's the skill of the craftsman more than it is the tools. I wholeheartedly agree with the recommendation for practicing multiple times on scrap MDF in order to get a feel for how you need to get things to fit around the sink. Once you get a practice panel exactly right, do two more before you start in on the real thing and use one of the perfect ones for a jig to draw your perfect template line.

Thank you all for your suggestions! I will let you know how it goes.