When I started the development of my game according to the then current Steam Hardware survey almost 10% of the gamers still only had Shader Model 2.0 available so I decided to write all effects (some of them gameplay related whereas they could not be optional) with the restrictions of said version.
Today the percentage is a different one, less than 1.5% of the Steam users have a graphics card that does not support SM 3.0, and as the restriction to SM 2.0 notably limits my ability to write effects and currently even prevents the implementation of one gameplay element in a level I am thinking about a complete switch to SM 3.0, meaning that my game would not run on weaker graphics cards.
Is there any reason that speaks against this choice?
I have written almost 200 shaders so far for my game, all compiled with 2.0. Does it have a benefit if I compile all of them with 3.0 instead? Only a few of them have an "if" statement, does 3.0 handle those differently?