A gentleman named Robert Ellis does a not too long but good and thorough video on mechanical mods and safety. The video let's you know everything you need to get started with mechanical mods. I think what people are trying to tell you is that if you don't know the basics regarding mechanical mods, such as when to tell by experience when voltage has dropped up, by things such a somewhat subtle but noticeable change in vapor production, a difference in the sounds of your coils firing, etc., then you are facing significant risks with sub-ohming. While the concept of using a mechanical mod is just essentially using a personal vaporizer that contains no electrical circuits, sub-ohming is essentially pushing your battery to the limits. Every battery has a different amp limit, exceeding that at too fast of a rate can cause catastrophic consequences. If your battery goes into melt down and starts heating up too quickly, fails to vent properly it essentially becomes a pipe bomb. Hence the extreme warnings of caution you find on this thread. With a regulated mod you are able to monitor your resistance, and due the circuitry when the battery becomes too long to fire at the required volts it simply doesn't preform anymore. With a regulated mod the circuitry controls things such as voltage/watt output. Since a true mech has no such circuitry, the resistance is up to the build you put in to it and the batteries you put into it. Depending upon the build, theoritically you could be vaping at much higher watts then some of the more powerful regulated mods out there like the Duke and Raptor even.
It's good that you have the Sony vtc5's which have an amp limit of 35a I believe, because not all batteries, even "IMR", high drain batteries are created equally.
Then there's the whole matter of shorts, hotspots, things of that nature. You will need to be able to trouble shoot common problems that arise when building your own coils. If you are not familiar with how to do so it is important to know how to, any adjustment you make to your coils has the potential to significant alter your resistance, and when sub-ohming you need to know to the hundred if not thousandth what your build is IMHO. I really hope you give this considerable thought before you go forward with the sub-ohming, and purchase all of the necessary equipment to monitor your battery condition. If you batteries get the least bit damaged, such as the plastic covering, discard them correctly and immediately.
I just woke up and the above was a challenge in and of itself to produce. If I think of more I will include it later, good luck!
Just wanted to add that under sub-ohming conditions, just like with increased wattage you will go through the e-liquid much faster! Your builds have the potential to produce much more vapor and thus lower nicotine levels are typically needed. You could notice a drastic difference in flavor on some of your liquids as well.
