I live in California. Most granite/marble/quartz here is 2cm although 3cm can be found. Cabinets have to be level no matter what. I have Caesarstone on my perimeter counters that are 3cm with no laminated edge. My island is 2cm marble with a mitered edge that doubled it to 4cm. My butcherblock counter is about 1 1/2" thick (a little less than 4cm). So all counters are a different thickness and I don't even notice the difference in thicknesses. I think the thinner edge is slightly more contemporary looking, but it's really up to what you like. Plywood with metal supports on the island before the marble was installed: 3cm Caesarstone (Arctic White), 2cm marble, 1.5" butcherblock:

I've been routinely quoted a 20/30% price difference between 2cm and 3cm quartz, with basic fabrication. If you think about it, you have 50% more quartz ... The price difference was enough to pay for a mitered edge (=looking thicker than 3cm) for countertops intalled against a wall (not on an island, because there are more edges).

You can save some money by going with 2cm, but you they will have to "double up" the edge, so there will be a seam line where the two pieces join. How noticeable this seam line is depends on the quartz (and the quality of work too, I suppose)- the ones with larger pieces tend to show the line less. I've seen edge joints on counters where I noticed it immediately, and on others I could only see it if I got up close and looked for it.

The difference with quartz is that the manufacturer warranty it and installers are certified by that manufacturer and must use their specifications and requirements so the warranty is good. They won't give you the same leeway to come up with unique solutions sometimes. I would contact Zodiac and find out what requirements they give their installers for that size and type of overhang and then work from there. You can probably find a telephone number or email on their website. Sue