I never used Answer or FRER to be honest. I bought a bunch of IC cheapies and got my first 2 BFPs on that (I had to dip twice because I thought I'd dipped wrong). Then I ran out and bought 2 CBE Digis and dipped one of those with another IC and got 2 more BFPs. In all I tested 13 times, primarily with the cheapies.

I never had one that wasn't obviously positive within seconds though.