No need for the 4". Really. You can also put an outlet bar/plug strip running directly under the upper cabinetry so whatever tile design can run uninterrupted. Far cleaner lines and should not run into any code issues.

fyi, i was thinking about using the 4 inch lip also because some of my backsplash tile is glass, worried about breaking/wear and tear

My decorator says no

No, will squeeze the size of the backsplash area
Feel free to check out my page in the backsplash projects for ideas

It's easy to say no but look closely how the outlets fit nicely within the 4" splash. This eliminates the typical location which would be in the glass tiles. Only other way to avoid the outlets is to install under cabinet outlet strips. Also be aware that anytime you install a tile backsplash directly onto the counter you must deal with the grout and with two converging surface cracking is inevitable.

No 4". Should not be a problem with wear and tear with properly installed products. Where two dissimilar materials meet you use a flexible caulk not grout, so cracking is not an issue.