With demo you need to follow your squads and spot it and with old demo you need both attention and the sweeper.
I'm not disputing that it's harder to counter demo, my point is that the loss is of much greater consequence if you don't happen to sweep the teller, which I think offsets that difference.
This leaves the much more relevant issue, which is that both can instant delete full health units. I was a bigger fan of the model capping for demos, and I think the parallel change for the teller would've been nerfing it's damage slightly.
Demos are currently useless, is anyone going to tell me that the teller will become useless if it merely reduces a t70 to 20hp rather than killing it?