A mirrored cabinet back can show the rear of a sculpt without turning it around. It can also double the visual clutter and reflect the room behind you. The best choice depends on the view you want to enjoy, not simply whether a mirror makes the cabinet look larger.
Test the main viewing angle
Stand or sit where you normally see the collection. Think about what the mirror would reflect: a plain wall, a bright window, cables or a busy room. Those reflections become part of the display.
If a cabinet has an optional mirrored back, compare photographs taken from similar angles. A close product image may hide reflections that are obvious from across a room.
Consider the sculpt's rear view
A mirror is more useful when the back has details you actually want to see. For a figure with a large opaque effect piece or a plain rear surface, it may contribute less than expected. Avoid making the collection more crowded just to fill every reflected gap.
Keep figures and projections clear of the backing. Do not lean a painted accessory against glass to stabilize it. The manufacturer's base and supports should do that job.
Simplify light and backgrounds
Move lamps before deciding that a figure needs stronger lighting. A light reflected directly toward the viewer can compete with the face. A plain background may be easier if you regularly photograph the collection through the doors.
When choosing a piece from Super Saiyan Sphere, look for rear and side views as well as the hero image. Those views help you decide whether a mirror adds meaningful detail or whether a simpler background gives the sculpt more presence.
Related guides
Lighting an Anime Figure Display Without Hiding the Details · Photograph Anime Figures Through Glass with Less Glare