To anyone who says that the difference in tax rates is not material, or may only be a 'few hundred' or 'few thousand' francs, it's worth remembering that there are a number of variables that contribute to how much you'll need to pay in US tax. This includes:
1) Whether you're under or over the FEIE limit
2) The tax rates in your canton
3) The size of your salary
If you're under the FEIE limit, it's pretty clear that you're not going to end up with an additional US tax liability.
But this is Switzerland, so it's dangerous to assume that everyone automatically earns CHF120'000 a year. Yes, if you're Mr. Average EFer, living in Baselstadt (with a relatively high tax rate) and earning CHF120'000 a year (just a smidge over the FEIE limit), you'll probably only have a small additional US tax liability.
But if you've taken a job as a Supply Chain director for a multinational who have based themselves in Zug for tax reasons, and you're on a salary of CHF250'000 with a further annual bonus of CHF100'000, a CHF50'000 relocation allowance and private school tuition for your 3 kids (not an entirely unlikely situation for some on here), you'll find that the combination of your salary (call it close to CHF500'000 when you factor in the benefits-in-kind) and the very low rates of personal tax in Canton Zug mean that you're likely to end up writing a pretty large check to Uncle Sam each year with quite a few zeros at the end.
This has two implications -- first, it means that you need to be aware of what your likely liability is going to be. Second, it means that you may make different choices than a Swiss person would: for example, it costs a fortune to live in Canton Zug. You might choose to forgo the tax benefit of living in Zug and move to a higher tax canton where rents are cheaper. For a Swiss person, this is a zero-sum game (the reduced rent is countered by higher taxes) but for a US person, who will end up paying the difference between their Swiss tax liability and their US tax liability, this will save money overall.
This is definitely a case of one-size-doesn't-fit-all. Do your sums, and particularly if you earn well above the FEIE limit, consider your tax position before making commitments.