RDMoto are the only ones I've found which wrap the lower part of the engine. All the other brands only protect the upper areas, but imho those areas are not at risk. The handle bars will keep the upper areas away from the ground. The lower part of the engine is probably pretty safe on pavement, too, actually. The little nib on the bottom side of the foot peg contacts the ground, as does the end of the handle bar. Everything in between is off the ground.
If the foot peg comes off in a slide, now there's some risk to the lower engine.
Or, if you're on dirt or a rough trail, the uneven surface can penetrate through to the engine. But again I don't see the upper parts being at risk. Your turn signal sticking out is the biggest problem in any tip over or slide because it sticks out past that line from foot peg to handle bar. I've dropped my '15 twice at zero mph. Once in the garage, once in a parking lot. (Nobody here knows me, so I can admit this without too much embarrassment). Both times the front turn signal hit the ground and cracked the fairing piece it attaches to. I've replaced the front signals with R&G micro LED signals. One time the factory luggage boxes were attached, the other time not.
Sliders which attach at that mid point in the frame may be quite adequate to protect the engine in a drop or slide on pavement. Bars wrapping the upper area won't add any protection imho.