It Builds 'Character'

The Characters in my Noir MMO should be customizable.

In WoW, there are 6 or 7 face templates to choose from for each race, a few hairstyles, etc.
I think this would work to a degree in a Noir universe, but limit the styles to the times. In other words, there would not be a 'Farrah Fawcett' hairstyle, etc.
But the face should be fully customizable.
Apparently Star Wars Galaxies' customization even included arm/leg length, and many other options that make WoW seem quaint and under-developed.
Even Vanguard's character/armor models are much more graphically pleasing, but you can only enjoy it at 50% the fps of WoW, after it 'pops' in, and only until it freezes your computer.

So how much does character customization affect frames per second? I have no idea.
The real question is, "How much character customization would you sacrifice to run your game smoothly?"

What I can see happening is this:
Noir is such a "genre" niche that the tendency would be to start creating archetypes (i.e. Femme Fatale, Guidos, Bogarts, Irish Cops, Scrawny Stoolies). Maybe ok as unimportant NPCs, but not as you.

But at the same time, would there be a huge loss if you couldn't give your character surrealistically long arms?

I think... yes. There should be long arms.
Of course.