I have all 3 regular bracelets and have been wearing them (only 1 at a time) for a variety of workouts - The Love is the most secure and comfortable for most workouts and yoga styles, however you'll need to be careful with movements that require your wrists to be close contact with the floor, or equipment (e.g. bar or ring work, or anything with CrossFit movements or similar), which may damage the bracelet - not talking about superficial scratches here! Depending on the fit of the Love on your wrist, the lock mechanism on the inside may also dig into your skin at some angles (e.g. weight training) and leave a mark.
Both the Ecrou and JUC have popped open for me during certain movements like handstands and forearm balance, because of the wrist extension pushing against the bracelet's lock. They may also cause discomfort for certain yoga poses (e.g. binding poses) due to the protrusions but at least you can easily remove them as needed. The Love is mostly flat (except the lock mechanism on both ends) so I find it much more comfortable.
My recommendation is that whichever bracelet you choose to wear, avoid stacking them as not only would it cause more scratches, but having more rigid items around your wrist during exercise may increase the risk of injury.