ORIGINAL: Prince of Eckmühl
Which comment of mine are you alluding too?
The comment about Type G's production numbers, "twice that of ... [] ... Ausf. H".
Without having checked Jentz yet (I will tho), web-sources suggest that these upgrades have not been applied to the entire hull, nor to the turret frontplate or gun mantlet, let alone to the front glacis. Most sources refer to this upgrade as partial additional armor applied to "critical spots". It's most likely in Jentz regarding what spots had been treated that way. I, for one, don't like to take a game as source for historical details, especially if it comes to Battlefront's portfolio, which contains quite a few errors (ie. in TOW).
According to the sources on the web, and that's what I recall from literature, these plates weren't welded, I just checked a few webpages (photos: i.e. on
www.waffenhq.de), these plates were bolt-on.
They were mainly upgrades for the driver compartment, as the driver compartment featured the only vertical part (only 9° from vertical). The front glacis wasn't upgraded either, so the only part receiving another 30mm-upgrade was the front part of the lower hull (23°), just below the (short) front glacis which incorporated the front lights. The add. plates consisted of face-hardened steel.
I wouldn't call this "heavily armored". Still, the Panzer III Ausf. H was basically immune to all enemy guns/calibres used at the time - at least at medium and long ranges, IF the enemy did aim at the upgraded parts. The Russian KV and T/34 could crack the H version though, while being largely immune to the Pz III gun (before the KwK 39 L/60 was used).
EDIT: There was a famous event in Russia (Battle for Krasnogvardeysk), Russian Lt. Zinoviy Kolobanov commanded a group of 5 KV tanks, on 14th August 1941, which killed 43 tanks and some anti-tank guns within roughly 30 minutes. His tank alone killed 22 tanks, while German tanks and anti-tank guns scored 135 hits on his KV - without effect/penetration. The German tank group, part of the 8th PzDiv, mainly consisted of PzII, with a few PzIII. But even the PzIII were torn apart.
KV and T/34 weren't available in huge numbers at the time, though.