"Yes" for Apple watches. We tested the Apple watch using an Apple watch band worn in the traditional wrist position and an Apple watch worn on the SHIFT band. Through a series of exercises the watches gave similar results. We have not tested other watches using native heart-rate or pulse monitors.
It is easy! We include a lug with your SHIFT that fits into the Apple watch. Slide your watch off it's wrist band, slide it onto the SHIFT band. When you want to change it back, slide it off your SHIFT and slide it back onto the wrist band.
We have worn the band with many running, cycling, and sailing gloves. Our advice it to wear it under the glove, adjusting the glove a bit so as not to cover the watch face. We have also adjusted the band longer and worn it over gloves. Your choice. We're focused on making it flexible.