i just bought a brand new Panasonic standard deluxe 1hp model. The outdoor unit was making strange noise and i had to call Panasonic to come and check. Turned out there was something loose in the compressor. If the sound doesn't sound right to you, just write to their customer care to call for service. But yes, i would agree that in general, the Panasonic outdoor unit is pretty noisy unlike the earlier generations. The quieter outdoor units for non-inverter airconds are carrier/toshiba and mitsubishi.

i'd advise you to think twice about getting a Panasonic aircond. Both my Panasonic airconds gave me problems unlike my Toshiba (2 units) , Mitsubishi (2units) and Acson (1 unit) which have all been running for more than five years without problems. Both Panasonic had electronic board problems, and one with additional fan motor problem. One Panasonic aircond gave problem within 1 month and the other within 2 years gave problem. The Mitsubishi and Toshiba indoor and compressor units are quiet. The Toshibas have been running for more than 10 years without any problems. They are switched on for almost 12 hours every day. Acson/York compressor units are well known to be noisy and gets noisier with age.

i'd recommend Mitsubishi inverter. Now that you mentioned it, I have a Hitachi aircond in one of my apartment. Compressor quiet but indoor unit is noisy and it spoilt once, the capacitor spoilt.