I've been in the building/construction industry for the past ten years and have seen so many different construction methods of building or framing walls. I think it all depends on how you frame your walls or how you've created your modular system. Without a doubt if your wall is a solid state wall that is framed like traditional building 16 or 24 inch on center studding I'd go into the ground with a wedge anchor through the sill plate instead of Tapcons because they break and spin out to easy if you don't drill the pilot hole correctly. Wedge anchors are drilled in with a hammer drill and if you need to remove them you have two options. Option A bang them through the concrete slab and fill with cement fix or concrete adhesive or grind them off so they're level with the floor. I will also say though that I agree with Larry as well on a modular system. If your modular system is secured in three to four spots including top and bottom and into another modular panel then it would be incredibly hard to move and/or pull apart after it was standing. This is on the assumption your walls are constructed using 2x4s and adequate cross bracing. I think if you look back at Shane's progress pics for Disturbia you can see the traditional framing route. And I'm sure there are some great progress threads on modular wall set up in here too. I see both ways being successful if DONE CORRECTLY. Larry maybe if you ever get the chance you could take a snap shot or two of how you connect your modular system together at the top. It might help.