The main reason somebody would prerender their objects would be for very complex lighting. If you intend to have dynamic lighting as it seems, that feature is gone. There is really no more purpose to attempting this unless you go with static, directional light sources.

Two games to look at as part of this argument...

Wing Commander used the technique described here (at least in its first few iterations). The sprites, however, couldn't have been more than 16x16 pixels, and IIRC the game was a RAM hog in its day.

Aleph One uses OpenGL acceleration in ccombination with its original sprite content, and requires vast amounts of VRAM and bus bandwidth to maintain even 30fps with any nontrivial number of monsters on the screen.

Another game that uses a similar technique to this is Shining Force III for the Sega Saturn (one of my all time favorite games, and systems).
It uses pre-rendered sprites at I believe 8 angles (N, NE, E, SE, S, SW, W, NW) on top of a real time 3d landscape. But that is also using the fact that the saturn could do a ton of sprites at once (hence the huge battles in the game).