I know for myself, I'll see good versions and bad versions of the push at the Platinum level. Bad versions are easy to beat. They either show up later than they should, allowing me to get a few spines at my third and an extra round of units, or the forcefields aren't good enough to protect more than one flank of the Protoss army. In either case, I can pick off sentries and immortals early in the battle and it's pretty easy to beat.
Good versions of the push show up on time, leaving me with just enough units to win the battle if I engage perfectly. It's doable, but requires hitting evenly from at least two flanks, baiting out some forcefields ahead of time, maintaining solid injects during the battle and even with all that the right forcefields will crush me.
That being said, I don't have masters level mechanics, but neither do my opponents. If I execute perfectly and they don't I will destroy them. If I execute perfectly and they execute perfectly they destroy me. That's my personal experience at a Gold - Plat level.
As for counters, speedlings and speed roaches are all I have time to get out if they hit at the proper time. If they're late and I can get some infestors that makes all the difference. A couple fungals on the sentry ball, lob some infested terrans over the forcefields etc.