Some automatic transmission "expert" on another forum claims that an automatic transmission will shift firmer with 4.10 gears and softer with 2.92 gears - no changes except for gear ratio.

I can't think of any reason why this would be true, but I've been wrong before.

Anyone agree with this guy?

might be easier for a shift kit to chirp the tires with a lower ratio (4.10's)

The rear gear multiplies the torque. Whatever the transmission does as it shifts gets multiplied more with a higher rear end ratio. Makes sense to me.

The shift wouldn't change but the rear end would hit harder.

The transmission won't shift any harder with the 4.10 gears, but the shift will FEEL firmer because the 4.10's make the vehicle jump forward more at the shift.

Well, it makes sense to me that you can more easily bark the tires on a full-throttle 1-2 shift with 4.10 gears than with 2.92, but the guy wasn't just talking about full-throttle shifts; he also claimed that with taller gears (lower numerically), drive and reverse engagements would be softer, along with shifts up and down, full or part throttle.

Of course. The rear end makes it feel softer or harder. It doesn't matter at what rpm you shift the difference will be noted through the whole range.

Okay, guess I should look for the white flag icon. . . .

Seriously, I went from 3.23 gears to 4.10 in my Charger a few years ago and of course there was a lot of difference in how it ran, but I don't remember any difference in the transmission shift quality. Maybe it was so long ago I just forgot.