Hi Mark -
I agree with the 'potential' for high torque with the multiplication factor as you put it in 1st gear but in my experience, high power high torque cars break traction all to easily in low gears BEFORE any real high torque is developed/applied. When we snapped the quill shaft on Roys GTD many years ago, we were hard on the throttle in 5th.
When I broke a drive shaft on the car at Gurston Down hill climb last year (the ONLY one we've ever broken) I was attempting to pull off in 2nd (as usual) but miss-slotted into 4th!! - as the clutch bit and I booted it - BANG!! the drive shaft snapped cleanly. In second, flooring it normally just smokes the tyres and in 3rd if track is damp..
So it is from this that I consider the torque actually built up to be highest in 5th. As I once said on a previous posting, if the gearing offered a 10:1 ratio (eg very small dia wheel), the engine will never work hard cos the wheels will break traction, whereas reversed, with very big diameter driving wheels, the load to the engine is higher as it will not break traction so easily.
Of course, that is only my understanding of it and I am not a qualified mechanical engineer (electronics being my background) so I could be talking a load of old Tosh! (again).
Perhaps any 'mechi techies' on the forum would like to explain the theory....
ps - as the designer is Ex F1 I presume he did it that way for a reason. If I am able to contact him, I will post what he has to say....