Altitude.... helps in a few ways. Less atmosphere to look through. I believe that at 1500m (Lake Mountain is 1400m....ish) you are above 15% of the atmosphere.... and 50% of the water vapour in the atmosphere. Both help a lot.
Also... it was bloody cold up the mountain last night.... and cold air is always a lot less turbulent than hot air.
The only bad point is that the wind can pick up... got a bit breezy just about 11pm last night... reduced the quality of the Great Red Spot images I was trying to take... still got some, but they could have been better if the scope wasnt being buffeted. Not always breezy though... last time I was there it was quite still.
As for moving scopes... that is the main reason I went for an 8" scope... so I could move it with a lot more ease. Much easier to pack that up... can set up in the back yard... up the mountain... take it on holidays...
But.... the BEST bit of Lake Mountain.... is the absence of that horrid glow of light pollution from the city... nice DARK skies...