It's $100 every six months, so $200 yearly total. It would certainly be interesting to see their use patterns on those levels. It's still hard for me to imagine it being worth it to sub for the higher tier, at least from my use perspective.
They have an RTX 3080 tier that from looking at their forums people are paying for. They're billing it at $100 every 6 months. According to settings in some games it looked like the basic paid tier ($50 / 60 mo) is running Tesla T10 GPUs
I think the biggest problem with Stadia is/was that it requires you to purchase the games strictly for use with their service. nVidias GeForce Now service on the other hand utilizes your current libraries from Steam, Epic, & Ubisoft.
As for input lag issues I haven't really noticed much when...
Ok, so now that most people are on board and liking it with season 2 it's going to get cancelled. At least I think that's how netflix originals work.
On a serious note, definitely liking what they've done with it.