If you get the tire to hook well, it should shave some time due to the increased gearing.
And you are correct about the wheel/tire setup being easier to spin down the track. The only issue might be traction with the lower profile tires (but those super sticky tires -basically slicks should get the job done).
Traditionally, you want more side wall (tire flex) when it comes to drag racing.
Ever since getting my converter (3200), my 20" drag radials 305/35/20 just don't cut it. My car makes too much torque leaving the line and just wants to light up the tires. I definitely need a tire with more sidewall. I'm thinking of dropping down to 305/45/18s to get more grip.
I should be pulling 1.6x sec 60' with my setup, but my tires just won't hold the track.
But I think your reason is valid. Your car should definitely run faster if you get a good hook. If you were running different tires (with less grip), you'd be in trouble.