I have used this method successfully in the past with no problems - I run error trap in the game once I've installed the exported world, and get no errors (as opposed to numerous errors due to messy global layer).
Now, with Island Paradise, if I use this method, my houseboat does not stay connected to the port. I find that I need to enter EIG one more time, reassign the boat to the port, then save and exit. There are only a few objects left in the Global Layer this way. This was done with a fresh sims 3 folder with no mods.
I did also encounter some problems with trees/shrubs/flowers disappearing from only the resort (no other lots), but I suspect that may have been mod related, as with no mods, this problem does not repeat.