Generally I prefer nice clean simple lines to my guns. However, the prospect of night hunting, and/or camping at night in predator territory, makes a compelling reason for weapon mounted lighting.

As Greg said, a key aspect will be whether the arrangement is strong enough to withstand recoil.

Have you considered a shorter rail and something like the Crimson Trace Rail Master or Rail Master Pro http://www.crimsontrace.com/products/type/rail-master-pro Already of a size and weight designed for handguns.

Another factor will be holsters. Does the holster you showed hold the gun with the light fitted or does it have to be removed? This may not be a big issue in the long term as holsters are already being manufactured for light equipped semi-autos.