I've had FS Global 2010 for quite some time now and have installed it in FSX, P3D v3 and now v4.4. If you're still running with the default mesh even if turned all the way up to 1 metre resolution you might think you're getting a reasonable representation of the world's mountains.
I can assure you you're not. If you need any proof these two images were taken from the same position. The only difference is FS Global was enabled on one but not the other. The mountain is the Matterhorn - one of the most famous mountains in the world bordering Switzerland and Italy.
The longer load times are definitely worth it for the huge amount of extra detail it brings. No impact on frame rates either.
First with P3D default mesh set to 1 metre - the highest setting...
Now with FS Global 2010 enabled and 1 metre mesh enabled. Suddenly, the Matterhorn appears!