The f1116 (tax credit) only works well if foreign taxes are greater than US taxes. I revoked my f2555 (income exclusion) to make my taxes easier (I hit that point where it was just too much work). Everything was great until I got married abroad to a foreign national, then I had to file "Married filing separately" because my wife didn't have a SSN. This absolutely caused my tax filing to collapse, and now I have a bill from the IRS saying I owe a lot of money (really I don't, I screwed up on the math, but...damn).
It turns out I can get my wife a tax filing number so we can file jointly, and now I have to go back and revise a couple of years of taxes, and will ultimately wind up owing nothing (hopefully!). The IRS helpline really does help (I was incredibly distraught when I found out...getting a huge bill from the IRS for a tax filing 3 years ago is horrible), if you are an expat abroad, use it! But it is still a PITA!
I feel sorry for those in Switzerland, Hong Kong, or Singapore, where the exclusion only goes so far and you wind up paying tax beyond your credit, suffering high VAT and cost of living that those locales entail. You really need a professional accountant at that point to figure out how you can get relief (e.g. by using the Housing Exclusion). The big problem is that each country "works differently", and what is considered income tax in one country isn't the whole story (they might tax differently, like with a high VAT and usage fees, and what about taxes on health insurance and various social security fees you'll never be able to use?), you can still very well be exposed to double taxation.