Ouuh, I had overlooked that for the 3090s, I’d need a new psu for those for sure. Checked the reqs for the 4080s, and Nvidia is saying 750 w. Puts me on bubble. But I have a high end, 80 plus cert Thermaltake which has been great thus far, and. I suspect exceedes the engineering design margin Nvidia has in their requirements. I concur about buying cheap psus, don’t. 
Thanks for the reminder of that. That essentially makes this decision cost neutral. Worst case I underdog the gpu and buy a new psu later once/if I restock those funds.
And if 24gb vs 16gb at that juncture still isn’t an issue, then, I guess I should hold off until November.