I guess we didn't really consider these to be regressions, nor did we expect kernel developers to consider us, humble users of old but stable distributions ;-) However it would fit our goal for the kernel-ml offering to help upstream as much as possible with issues.
These kernels are not intended for production use, but provided as-is and as a means to help users to find newer drivers that can be backported, or detect regressions with drivers known to work. (Although they can be very useful nevertheless...)
I'll discuss this with the other team-members and see if they agree to report these upstream. Thanks for mentioning, Jon !