Rigid or deformable electron?

[Bob_for_short]

If we suppose that the electron is not point-like but smeared classically or better quantum-mechanically, what model would you experts prefer: a "rigid" or "soft" electron? I do not speak of the Lorentz contraction here, I speak of "mechanical" behavior in collisions.

Edited December 20, 2009 by Bob_for_short