Strange. I just tried a test with your settings above and my test post and test comment response both showed up immediately and after one browser refresh. With W3 Total Cache disabled, the fact it takes 3-4 minutes for new posts to show tells me there's another bottleneck in your WordPress environment.
I presume you've tested your blog with no plugins enabled and then with only W3 Total Cache enabled? Also, have you tried the suggestions by Frederick Townes in the thread you reference above?
Peace...