I stumbled across a question on whether yellow or orange safety vests were better for visibility, and it got me wondering - I have a vest that consists only of the silvery reflective fabric (and it definitely is reflective, I cannot pass a disinfectant dispenser without it going off from some meters away...). Now, I haven't seen any other cyclists wearing one of these, so I can't quite judge the visual impact - is it fine, or do I suddenly go from "barely visible" to "sudden (too) bright spot" in a way that is unsafe when a car's lights hit the vest?
I think your main problem will be when it’s not dark.
I’ve noticed with my Castelli Gabba jersey which is a really bright fluorescent yellow that people notice me much earlier at intersections or when they only quickly glance over their shoulder. The effect is especially noticeable on those rainy, foggy days in fall but of course requires some daylight or at least streetlamps. In ambient lighting silvery reflective fabric looks pretty close to stealthy gray.
At night I think proper lights and maybe good spoke reflectors (the yellow plastic kind) are much more important. The problem with reflectors is that they are unreliable. They only work if the other road user has a working headlamp which is close to their eyes (retro-reflectors reflect light straight back at the source, that’s why they work so well) and aimed in your direction. I consider front and rear reflectors a bad back-up in case your normal lights fail at the worst possible moment or without you noticing.
Large reflector surfaces can be dazzling, especially for car drivers using their high beams. So this could be a concern with a jacket which is one big reflector. But then again … road signs are usually much bigger and more reflective than reflective fabric or tape and their dazzling effect is bearable.