You can't beat real PBG data because slit moves with currents/tides. TZ Mapping for the USA covers three times the area as others for the same or lower initial cost while providing an unheard of update price of $20. No matter what, you get your monies worth when buying the USA TZ Map on XL. Here are some shots from the west coast of FL where you were asking. I am not a big fan of the changes they made to the Terrain Shading in the current version of software. We have asked they look into changing that back where the shading looked more natural. The bathy data varies but many areas you can see changes as low as every three inches. But reality is stuff changes slightly and moves. If you have PBG, I would definitely use it.