One can be as safe as the other given proper gun handling and good training. If you've been carrying a Glock I would stick with that platform and would not recommend a compact 1911 for a ccw. Also, the 1911 is a completely different platform and would require different training needs; another reason to stick with the Glock.
As far as calibers go, one is really not better then the next in the context of civilians needs for cc and if you choose a major service caliber from 9mm to 45 acp. If you are shooting 9mm currently there really is no need to change calibers, just choose a premium defense load from a major manufacturer with a modern bullet design.