Current win/loss rates (
www.coh2chart.com/) show a surprisingly even level of balance at 1v1 but as the games grow the axis / allies difference widens massively. There are debates about the value of these stats and also whether 4v4 can ever be balanced but I believe that there is a big disparity and its a big problem for the wider player base (who mostly play these modes) and enjoyment of the game.
Im not a big fan of the nerf / buff unit approach and certainly not on the scale that might be needed to shift win /loss rates on this scale - I think some subtle tweaking is needed to increase gameplay fun and reduce frustration but otherwise unit balance is quite good.
The problem as I see it relates to the synergy between OKW and OH and how increased resources and map sixe in large games benefits axis. Fuel scaling for maps (i.e. less resources from points the bigger the game size) has been brought up before but I see little discussion - it also feels a bit fiddly.
i would be interested however to see the effect of something simpler - making resource caches only benefit the player who builds them in the same way that opel trucks were changed. This would have the benefit slowing tech in large games for everyone and specifically reducing OH / OKW synergy. the danger is it might have some fatal effects on early mid game in 2v2 and the ability of OKW / OH teams to counter soviet t3 for example but then double OKW teams manage ok.