<>I want to know about the comparison in between using RCV420 and simple schematic as you have suggested ? I just want to know what good an RCV420 could do over the simple circuit ie using precision resistances and opamps . Cost is one criterion as RCV is way too costly.
I have used the circuit described umpteen times with no problems (you may have to recalculate the resistors, ckt from memory). There is such things as common mode rejection (can be improved in my ckt if lower gain is set) and speed where the BB ckt probably will do a bit better, but again, I have used the ckt many times.

Erik