If it helps, I have a Daikin Smart Inverter 12,000 BTU cooling an ~19 sqm bedroom, with 5.5M high ceilings, and it does the job just fine - at night

There's generally not many heat sources in a bedroom, and they're generally only on during night time when there's no sunlight issues either. If it will be needed during the day, or you have, say, a 500 watt plasma TV that's on for hours, you might want to consider going larger though.

i am interesting in buy this unit. Is it quite? Can i ask you how much you pay for it?

at the moment i am thinking to buy the daikin smart inverter or the mitsubishi MSY-GK13VA

thanks in advance

I Bought mine last year for about 21K + install. It looks like they're still available now for 21.7K: http://gaincool.com/index.php/th/%E0%B9%81%E0%B8%AD%E0%B8%A3%E0%B9%8C%E0%B8%9A%E0%B9%89%E0%B8%B2%E0%B8%99%E0%B8%97%E0%B8%B8%E0%B8%81%E0%B8%A3%E0%B8%B8%E0%B9%88%E0%B8%99/%E0%B9%81%E0%B8%AD%E0%B8%A3%E0%B9%8C%E0%B9%84%E0%B8%94%E0%B8%81%E0%B8%B4%E0%B9%89%E0%B8%99.html

When first turning it on in a hot room, it's not super quiet, no - once it slows down the fan speed as it approaches/hits the preset temp, yes, it's very quiet.

Last question, inverter unit really worth to get?

Only worth when that machine runs for many hours a day.

My advice to a friend on her townhouse. Inverter units for bedrooms and a normal unit for the living area.

Precisely