Starcraft 2 units: Ground control to Mule, report to mineral line!

I was recently a bit interested in MULE, mutant SCV with the failure - expandable and limited energy. Reading around unit explanations and forum debates, Mule is pretty controversal unit. Some Terrans find it very usefull. Some think it is useless and waste of time. Other races are divided too, between "doesn't care" opinion and that Mules are Terran's advantage.

I guess the opinions differs strictly based on individual player style. If Terran don't use mules maybe he never tried and what difference it makes. Every unit has what is has, the difference is in usage, or better, if you can decide, when, why and how you can use it. It stands very strong for Mules.

Mule, as any other "non-starcraft" mule is hard worker. It is Mule's main role. Terrans have mules to compensate other races boosts like Chrono boost, and Spawn larva ability. All of this is in role to produce units faster and in larger numbers in unit of time. Especially in early game.

Mules are fast in matter of resource gathering. Mules collect 270 minerals in their short 90 time lifetime. They work for 5-6 SCVs.
It takes only 6 time units from calling them from outer space till they start collecting minerals (in case that you target directly mineral patch, whish auto assign it). Considering minerals, you can clearly see in what situations Mules are good help:

- in early game to pump up initional mineral assets and produce early defense/attack units or buildings.
- after you plant new expansion to gather minerals before you can fully saturate the field with SCVs
- after your mineral line is rushed and/or destroyed
- to replace SCVs that you can put on gas without loosing mineral rate

I see different replays when high level users count on Mules as strong part of macro-mechanic. Mass marines with 5-6 reactor barracks is much easier in mid game, as they use no gas but only minerals. One extra free mule brings you extra 4 marines in 90 time, without interactiong your normal production.If you are Terran, try recall if you have ever been in situation when you need marines fast but you are starving and you didn't use any mule. It doesn't cost you anything but energy. I also noted that some player never build Planetary fortress but only Orbital command.
It is kind of loss because planetary fortress has 1500 hitpoints and do 40 splash damage. In the mid game if you call 4 mules they will gather 1070 minerals in 90 time. If you have 5 reactor barracks you can produce almost 20 marines (ok lets say 20) in the time before mules die.

Now if we compare this, planetary fortress do 40 splash over 2 cooling seconds, while 20 marines without upgrades do more then 120 damage in the same time. Fortress has 1500 hitpoints while 20 marines have around 1200. Of course, this is very rough calculation, you need some minerals to build five reactor barracks. But in mid game when you have everything set up it looks like Orbital command with Mules can be more effecient in sense of mobile defense production fast. So I vote for orbital command on every expansion. This may give you enough energy for Mules, scanning, or eventual instant supply addition. I have seen a game where few expansion mineral fields were constantly switched between players. One of tham was able to drop 7-8 mules to any new expansion gathering extreme ammount of minerals before the expansion was retaken by his opponent. Doing this several times extremly helped his economic stability and unit production under constant fight.

When you are used to have Mules around you will probably have more problems with gas then minerals. Gas can dictate your tech, but having enough minerals will help you replace lost units and buildings which doesnt depend on gas.

Well this is my noobish thinking. I can't show you example on effective Mule usage. Can't show you any of my games because I play too slow and sometimes I have plenty of minerals even without Mules. Ok, so I am just "smart pretending" newbie.