Sorry, my mistake, I thought you were accusing me of saying the StuG would be unable to effectivly combat those vehicles at range.
And your numbers are off by the way. Our L'43 gun is rated at 90mm penetration at 2000yds, which means it should be able to engage ALL of those vehicles (save the KT) from beyond 1300yds. T-34 hull only provides about 85mm at line-of-sight thickness, and the M4 only has 95mm at LOS thickness. Lower hull of all vechles with sloped armor is a well known weak spot.
The Panther's turret is 100mm thick, the M4's turret is 63mm thick (with an 85mm gun shield), the T-34's is 90mm thick.
So a StuG armed with the StuK 40 L'43 would be capable of effectivly engaging the panther out to around 1600yds, the M4 to around 1300yds (based on my expierences fighting them in-game with the L'48, and offline with the L'43), and the T-34/85 all the way out to 2000yds.
An L'48 armed StuG would be able to engage the Panther out to just short of 2000yds, the M4 out to about 1600-1700yds, and the T-34 out to (an estimated) 2300yds.
Also the StuG's extra 30mm of armor over the Panzer IV F (StuG III Ausf. G had 80mm, as did the StuG IV) would likely cancel out the extra use the turret would give. IMO, the main reason people drive the Panzer IV F over the Panzer Iv H is that you get an ENY of 35 (I think its 35 anyway), still get the second best gun mounted on a free tank, and you're only slightly easier to kill.