can be set and fine tuned - even if it takes some fiddling and trying -
dual-pad monitors have fewer false alarms.
The Angelcare monitor also doubles as a sound monitor, has a
temperature sensor in baby's room with display on the parents unit
(even an alert if the temperature moves out of range).
There is also a built-in night light and the units work with batteries
only - they are rechargeable though.
If you have a healthy baby and feel confident about
supervising her regularly (having her in your room the first months is
recommended anyway), you will most likely be fine without this
kind of monitor.
If your baby, or any of her siblings, have had serious breathing stops,
have (had) sleep apnea or near-SIDS experiences, a baby movement
monitor can be an important tool
to help supervise her. Your doctor may also advise this.
If you're naturally anxious or know that you sleep very deeply and
are afraid you wouldn't hear or feel when your baby is in trouble, then yes you might feel (and sleep) better thanks to one of these.
In any case, always discuss it with your doctor or health advisor.