The reason for the pc breaking is due to the knit lines low strength. Pa tends to weld better due to its semi-crystal structure. You can make better of parts by optimizing the process and tooling for a amorphous resin. Gate sizing must be increased, runner sizing upsized as well, removing any sharp corners/stress risers from mold and runner path. More mold temp as well as optimized fill rate and hold time/ psi. You could also add glass to the pc resin. It really depends on end use as to which resin will be better. A polyester resin may be a better choice due to cold impact and water swell.