I too just upgraded my brakes. Congrats! The night following the install I definitely didnt go through a straight 2 mile tunnel while there was no traffic and test them from ~150-35. Though im certain that in the aforementioned theoretical situation the car stood me practically on my toes the whole way and there was zero...zero steering wobble before or after. I do still need to properly bed them in tho which should have been done before I theretically did that. Endless recommends 5-8, 85-25 decels in a row for their pads for proper bed in (should be a good program for any semi-track pads) . They should smell bad and possibly smoke when you do this, be aware, just means its working.
Most of that lost rotational mass is probably from the center of the rotor, a place of arguably less benefit.

Cheers