Four single-rank sticks or 2 dualrank sticks is what you should aim for, no more than that. 8 ranks total is bad for the IMC, you will most likely have to drop clocks. So it's no point, really.
And B-die, it is overclockers RAM. You end up spending 200 dollars more for maybe 5% more performance, in some cases. You could literally put that 200 dollars towards a better GPU or similar and gain a lot more performance. B-die is a bit of a waste of money, except for overclockers, where even 1% counts, in competitions.
And when it comes to single vs dualrank: https://www.techspot.com/article/2140-ryzen-5000-memory-performance/
It matters at 1080p, in games. I tested it at 1440p, my native resolution. The difference was 1 fps avg, maybe 3 fps on the 1% low. Nothing I will ever notice. So 2 singlerank sticks vs 4 singlerank sticks. 4 singlerank sticks become dualrank because there is 2 ranks per channel.