what's heavier a ton of feathers or a ton of bricks ...
always loved that one.
Don't you have to replace tubes more as UV runs low, but combi does seem to maintain UV longer? then to the extreme there is traffic, fuel, shipping, time etc. I suppose it is what is off set against it long run.
What I have noticed which is an absolute joy is heating costs are down cause those D3 Arcadia chuck out some heat, and what I absolutely love is that Im sure im getting good UV on my skin too sitting right next to one !! Pure genius. CB