It should be mentioned that there are lots of non tax avoidance reasons to go offshore. The biggest ones are asset protection and incontestable estate succession.

IMHO, if your net worth is over about 250k (or lower if you have a high risk profile) your assets should probably be held in an offshore LLC, trust, or foundation. This makes them effectively untouchable by lawsuit, divorce proceedings, seizure, etc.

If you are concerned that your will provisions will be contested or that a lawsuit between siblings is likely when you die, offshore estate management also makes those things impossible.

Since in only costs 1-3 thousand US to set up effective offshore asset management, and maintaining it is 200-1200 a year, it's a small price to pay for peace of mind.