CN-0312 why not use ADG733 to replace ADG633

Hi support:

CN-0312 why not use ADG733 to replace ADG633?

For AD8615 circuit, the on resistance of ADG733 is smaller than ADG 633.

If use ADG 733,  the performance of circuit will get better?

It is only cost consideration? 

For the LED driver, also use ADG633.

How large resistance and how large leakage current could I choose for this switch ?  50ohm, 100 ohm? 

How to evaluate this resistance and leakage current ?

Or there are other more important considerations?

best regards