Hi guys,
From what i think, no matter what company you get the air con from, the most important is after-sales customer service and support. It's always better to get your air con from bigger companies. I have ever heard of stories from various customers buying from smaller setups and received no support when they need (ie. installation problems, gas leaks, water leaks from trunking etc). Installation warranty is also one thing to consider. No matter how good an installer/company is, there is no guarantee of 100% problems-free. It's like buying big/small, you win or lose.
I work in one of these air con companies as a QC, so i have really seen many many good + f***** up installation work. Air con condensation, on the other hand, depends on what type of insulation you use (normal or upgraded insulation). If there is a need for the piping route to pass through the toilet (especially new HDB designs in Punggol), it is ALWAYS RECOMMENDED to upgrade your insulation. (temperature difference between bathroom/rooms/living room, especially when bathroom is usually cooler than the rooms). If non-upgraded insulation, you may see condensation very soon. A thicker/upgraded insulation can prevent this problem from happening in the near future.