I have done several successful flat bar conversions, using Alivio combined brake/shift levers. 7 and 8 speed. Something to watch out for with the brake levers is whether the cable pull can be set for normal brakes, i.e. calipers of cantilevers, as opposed to V-brakes. Also you may need a MTB FD, especially when running a triple, as the cable pull differs between road and mountain. I don't remember having problems with doubles.