No direct knowledge of the SB Acoustics SB10PGC21-4 3'' Fiber Glass Cone Full Range. But good specs on data sheet. I don't like the big rise/peak across the top octave though from 10-20 kHz. You will likely need some sort of EQ to adjust the response in this area. Even though a line array can tolerate some rising response, this is more of a challenge than the SB65.
Looking at the B3s square. It looks good spec wise but no response curve on the square frame version. Readers report roughness down low and up high in frequency.
What I did was to buy samples of several drivers to listen for responses. It does not tell you about how they work in a line but general knowledge and your measurements can be attained.