Shooting you Sig226 will put you in Production division...this probably ruled by the Glock..but it requires all guns to be DA/SA or safe action..all guns are scored minor (9mm).I think you will be fine...
The 1911 pretty much rules Limited and Open, and a favorite in Limited 10..because of the SA..Glocks do well in Limited and L10 too..
Big thing is to make sure you have a good holster and enough magazines..most IPSC matches shoot about 100 to 150 rounds with field courses in the 22 to 36 round area..so if you are shooting a L10 or production div. gun you would need at least four mags..one in the gun and three on the belt..
anyway..good luck, have fun, shoot safe..