1-I wouldn't, why would ? To each thier own.
2-You could improve your 2-channel and still keep your 5.1, just adding a decent 2 channel pre would help and ipmroving on that would be a better amp/amps for the main speakers. Another option would be an integrated, this would take care of both and again you could still keep the 5.1 going.
3-I have an Anthem 3 channel, it's ok for HT, but I wouldn't recomend it for 2-channel.
Jeff
2-You could improve your 2-channel and still keep your 5.1, just adding a decent 2 channel pre would help and ipmroving on that would be a better amp/amps for the main speakers. Another option would be an integrated, this would take care of both and again you could still keep the 5.1 going.
3-I have an Anthem 3 channel, it's ok for HT, but I wouldn't recomend it for 2-channel.
Jeff