I have a GTX 1070. My biggest current issue is VRAM. Should I go for an RTX 3060 or RTX 3090?

King-Of-Tha-Dome

So, I'm finding out that the 8GB VRAM limit on my 1070 is becoming a limiting factor for my renders. I'm deciding between upgrading to a 3060 or 3090.

Essentially, this is a tradeoff between performance and value. The 3060 gives me an extra 4GB of headroom at a nice pricepoint but is slower than the 3090, while the 3090 ensures I don't have to think about VRAM ever again but costs a small mortgage to buy.

Let me preface that I'm aware the 3080 Ti exists, but given that it (currently) costs about $900 more than the 3060 with the exact same amount of memory, I'd just go for the 3090 anyway.

My questions are:

1) How much of a performance increase can I expect going from a 1070 to a 3060 for Daz rendering?

2) From a rendering perspective, how much faster is the 3090 than the 3060 (e.g. if a render on a 3060 takes 5 minutes, how long would it take on a 3090)?

3) What is the practical difference between 12GB of VRAM versus 24 (e.g. will most scenes on average fall below 12GB of VRAM used, or is it not unheard of to get close to 24GB of VRAM used)?