If you solo and most of your trips in the Sierra are 2-4 days I think you will be fine with the small bear cannister. You can always rent a Garcia at the trailhead for the occasional longer trips. If you are always going to be with a group, the the 2-4 day food for 2 people will be right for a regular size bear cannister. Two people carrying one regular size bear cannister is less weight then both carrying a small cannister. If one person carried tent, fuel, and cook gear and the other the bear cannister and food, that is somewhat an even load for each for both weight and bulk.

If you only go out a few times a year in places that require a bear cannnister, I would rent the bear cannister.