Little trick to try once you do decide to pull a plug - make sure the plug well is clean first - then squirt a little bit of PB Blaster or Deep Creep in the hole before "breaking" the plug loose. Just break it loose, then let the oil work its way through the threads for a few minutes, then carefully remove the plug.
My understanding is that the 2-pc spark plugs break because of deposits over time building up around that extended tip, and they typically break around where that tip is welded onto the main spark plug body. The penetrating oil should break those deposits down over time enough to where the plugs can be removed. If you meet resistance at any point, stop and put more oil down the tube and let it work for you.