It all depends how much you love your dog, how long will you be living in HK for, can you afford the cost of moving your dog here and also if their health can take the move.
Our cat managed the 4 mths in quarantine in Pokfulam, no worries and most visitors go to see their dog or cat on weekends, as told to me by the staff. I went everyday, but the facilities are clean, if basic and you can walk your dog around in a special 'play area'. The staff I found to be friendly - just speaking from experience, and no, our cat is pretty spoilt but was not 'emotionally or psychologically affected' in any way. You can provide your own food for your dog, if preferred.
As for living in the Mid Levels, it is a good area for dogs to walk and interact socially with other dogs.
Just don't decide to adopt a dog ( or cat) here in HK then abandon it after a couple of years if you decide to move.....
The 30X bus goes quite regularly from Exchange Sq or Connaught Rd (outside Maria's bakery) and stops outside the quarantine centre.
Either that or a $60 taxi ride...