Quite true, MG42 is the key to the early game for Ostheer. My conscripts already complain that "The germans rely on MGs way too much.".
The problem is that a 10 minute PzIV won't help. The SU-85 *will* hit a minute later or so, even if you hold both fuel points. It's a much better idea to mindgame the Soviet by delaying the PzIV for 2-3 PGrens (who are pretty annoying to SU-85), which will also give you a chance at gaining map advantage, while he won't have enough troops because of his SU-85.
I've said it elsewhere already, the SU-85 needs to come out a little later, to encourage the Soviet to not overgo T3/T-34 and force some Zis-26 out of him.
That's a pretty flawed argument, upgunned Guards are able to hold their own against all infantry very well and their grenade is pretty strong. I'd go so far and say Shock Troops are completely useless right now as Guards simply have too much versatility to ignore them.
Upgunned guards are a decent long range unit, their infantry damage is pretty lackluster from personal experience, however I agree their grenades are quite powerful - I find myself not being able to use them very often however because all my Muni is usually spent on Molotovs to get MG's out of buildings early and either AT nades + DP's/Button to kill early vehicles (fails anyways, way to go passive smoke doctrine)
Also we both know that 2-3 Guards can do a relative amount of damage to a P4 (not nearly what shreks can do) but no competent player is going to just drive a p4 into a bunch of Guards. One MG42 behind his p4 and all of my AT is insta pinned, forcing me to retreat or take huge losses while also not being able to do remotely enough damage to a P4.