Floating floors are a suitable alternative if you need to reduce the sound of footsteps crossing the floor above (impact sound transmission), whilst glued hardwood flooring provides much better sound conditions in the actual room of installation (reduced room resonance).
A room which has been glued down permits greater heat transference than a floating system. However, it is important to adhere to certain rules when underfloor heating has been installed - a maximum output of 60W per m2 and/or a maximum surface temperature of 27oC.