Angelcare monitor here (although we have now taken the mattress pad away).
It really helped with my paranoia with DS - I was terrified and convinced that he'd stop breathing. We did have a couple of false alarms when he managed to wedge himself like an L shape round the corner of the cot but I'd rather that than spend every night panicking! Agree with remembering to turn it off when you are feeding or changing them unless you are hinting that your DP should get up and help
I use an angelcare one in ds Moses basket he will be moving to a cot any day when DP gets round to building it! Ds is 12 weeks old and I bought it in the early days when I couldn't sleep even when lo did as I was scared he would stop breathing. As ds is currently in our room I just have to glance at the flashing light on the child unit to know he is ok rather than get out and try and quietly prod like I did early on. The parent unit is in the living room and the sound is good but not as brilliant as some digital ones. We've never had any false alarms but that might change when our wriggler goes in his cot- main issue is both remembering to turn it off when one goes to feed or change them in night but we've both managed to only do that once each in 3 months. I also like the fact it has a night light and digital thermometer. I think the night light has been good for teaching ds difference from day to night. We've had a few instances where we have turned bedside light off and night light on and lo will go from awake to sleep. When I was comparing prices I strangely found Argos was the cheapest around. Hope this helps