Salt grid is good, but not needed for it to work..
If the motor on the 5600(non SXT) goes out you can cycle it with out elect while the 2510 will need power to set to each part of its cycle.
5600 is all factory settings save for salt setting... 2510 each part of the cycle can be changed..
Motor goes out on the 5600 it is only one and for under $50, the 2510 has 2 motors..
The SXT has the control board and the cam motor... plus the SXT control board can run in the could be in the 200 range..
5600 can have the seals and spacers removed with fingers, while the 2510 can be done that way the tool makes it easier...
SXT with the meter has the gallon count with default days..
5600 has been around for some 40 years , the 2510 come out in late 90's
Both can take the same bypass...