A little off point, but here's my take on the marauder / adept match up... sorry for the length, I got carried away:

Marauders aren't actually that bad vs adepts w/ the proper micro. Medivac/Marauder w/ Stim I believe is slightly stronger in a straight up a-move fight. The difference is that it costs the terrans slightly more gas. The kicker is that marauders can effectively kite adepts forever as long as the adepts aren't using their shade ability. Marauders w/ concussive shell can slow the adepts, plus they have a 2 unit range advantage over adepts.

The reason most terran don't go pure marauder is because marauders can't shoot up and don't have high DPS against unarmored units, and they get rekt by immortals.

Also, a lot of protoss like to lead by shading their adepts right on top of marauders. Now, if the marauders are already backed into a corner, they can get destroyed. If the marauders are in the middle of the field with concussive shell, I hardly ever see terran shoot a volly and run away to begin kiting. They often just stand there and fight. Usually the toss's other units walk into the fight and kill the bio ball as they're being distracted by the adepts.

What I think hurts a lot of high level terrans that go M/M/M is that they tend to a-move their marine/marauder ball forward into the adepts, which naturally leads to marauders standing behind the marines. Marines get absolutely rekt by adepts, and if the marines are dying off quickly, that's a massive chunk of DPS that is removed from the terran army. The marines must ALWAYS be micro'd behind the marauders. Personally I think the terran should always stutter step their marauders just barely into adept attack distance, 4 range, so that their back marine line is always within 5 range, out of range of the adepts, but close enough to still shoot... that way the marines won't try to run ahead of the marauders, and the marauders will properly tank the damage.

I think terran can easily go heavy marauder play as long as phoenix aren't in the game. Phoenix are a heavy marauder army's worst nightmare.

One other idea I have with a M/M/M build is to use your marauders like tanks and split the ball. Marauders in a ball in the front and marines in a ball in the back. If the protoss chooses to shade onto your army, they want to shade onto your marines, but they may choose to shade onto the first ball of units they see. If the marines are outside of the scrum, they will absolutely decimate adepts.

I'm also going to try and start messing around with an early ghost + marauder play (assuming no phoenix). If adepts shade onto your bio ball, emp your ball and the adepts will see their health instantly cut in half and will die off very quickly.

When you're attacking a protoss who leads with adept shade, and is following behind with their rest of their army... keep running away. Think of the shade as if it's a siege. If the adepts warp, keep kiting away as you attack them to keep them separated from their army.

If you're backed into a corner in your own base, make sure you build a wall to stop adepts from shading on top of you.

If you're in the field and you have tank backup, put your bio in front of your tanks, not behind as if you're fighting a terran. If the protoss chooses to shade onto your bio, in hopes that the tanks will kill the adepts and the bio ball, wait until just before the warp, then stim your army back towards your tanks. Upon warping, the adepts will hopefully stand still while your army is getting clear of them, and your tanks will wreck them while they're balled. From there, push your bio back out front to take the fight with the protoss' main army.