Yep, like I said, you'd ignore the suggestion. From a time perspective saved going around a track, negligible to non-existant. On the street? Even less. The math is pretty straightforward, Grassroots Motorsports has done extensive testing on it, anyone but professional race teams don't care because it doesn't change anything.
Give up wheel stiffness? Oh lord, LOL
The last thing ANYONE should ever care about. Jesus...
People do lots of stupid things and spend lots of money on ridiculous things. Doesn't mean it makes any sense. You could be a rational person. Or not.
Note, I never said not to get 19's. You specifically mentioned shopping by weight, I said it doesn't matter. Don't change the goalposts in the discussion, if you want 19's, great, if you want to save weight, well its an awful idea for performance per dollar.
Go ahead, waste the money. Just understand for all practical purposes short of being in a higher end racing series, its a waste of money shopping for weight.