The way I see it, unless you need network data all the time (like, it's for work and you're in the field every day) I can't justify paying $100 more and be tied up in a 2 year contract just to have onboard 4G. I have 3G on my Galaxy Tab and use so little data I am cancelling it. On top of that, my tethering plan can be added and taken off at will (so no additional contract) and is cheaper than what I'm paying for tab data.
When you add in the faster updates, buying a data enabled tab makes little sense for most people.