I'm using this with my friend who plays toss, he generally goes 4 gate or 3 gate robo.
We've been on a tear when I do the 3 helion drop, transition to either banshees, or marine/tanks depending on what I see with the drop.
However, recently... it seems we've hit a bump as we climb higher and higher in standings and leagues. One thing that we seem to be having a lot of problems with are teams that do early aggression. When we scout, we'll see no gas and expect it -- but other times, we see 1 gas and go on with our build, except when I go to drop we usually get hit with mass marines/stalkers/etc.
Another counter that's hard to deal with I find are guys who go blink stalkers. By the time I drop my hellions, they are moving in to attack us. At most I have 3 tanks out with siege, but they just blink right on top of my tanks and we lose.
Any advice? One thing we thought of doing was, before I send my medivac+3helions for the drop (which is usually always exactly on time since the build is so efficient), I drop a couple of bunkers down at base and get our defenses set up... since dropping helions in 2v2 ASAP isn't AS important as it is in 1v1.