This is somewhat of an incomplete analsysis, because you can use light tiling with either forward and deferred. And that's pretty common nowadays. The real advantage to deferred is to save on quad overshading and balance the use of the GPUs. By making lighting homogeneous across the scene you'll have a lot better utilization of the GPU's resources, since there's no wasted pixel effort during the expensive lighting loop.

Downside is of course transparency and the need to dump your full material model into a G buffer...