The CB1 and CB3 filter models have the same dimensions, so either can fit inside the housing. The CB3 can filter more "junk" than the CB1 model (such as lead, mercury, MTBE, and VOC (volatile organic compounds)). Some municipal tap water can carry residual compounds even after treatment. If you consider your water safe from these compounds then you can use the cheaper filter. Filters should not be cracked. Yours must have been crushed during shipment. I know it is a hassle, but you should have filed a delivery damage claim. If the crack is within the carbon block, then it is possible for water to go through the filter without being filtered. Then the filter would not be doing its job.
As a side note, the CB3 filter model design was changed in 2008 which made it about 1/8 inch taller. This resulted in installation problems with people who had the older Omni filter housings. They could not close the top of the unit. The Omni rep said to remove the gaskets at the end of the filter to allow it to fit in. Not sure if this is a practical solution or not.