As per title, if the hub remains the same, would 2 different brands of rims with the same ERD use identical spoke lengths?
I would say yes
Yes, assuming the ERD actually *is* the same. I understand that there can be some variation in how it's measured, but in my (limited) experience it has never been a problem.
That is the point of ERD.
Lets say I had your hub too and I bought rim B, whilst you had rim A, we both use the same spoke calculator and come to the same conclusion. We arrive in the LBS at the same time, you are in the queue in front of me, and I overhear you asking for the same spokes as I want and the bloke in the shop says we only have 64 left.
Do we:
a) have a ****ing massive rumble?
b) end up having three kids and live happily ever after in a terraced house in Crawley?
But at the end of it all, we would need the same spokes..
Unless one of them is asymmetric.
The ERD stated by the manufacturer should account for asymmetry
Why not just buy a spoke and screw it into nipple to see exactly how much thread shows to confirm whether it is going to be too short or too long a spoke. that would be my first go to thing.