The baby beast (really any subtank) can run thinner liquids but its not the greatest. You run several risks that happen frequently
1. Burned coils- The low resistance of the coils calls for more power, more power gets the coil hotter, juice burns off quicker resulting in some cases in the coil not priming quick enough to keep up with your vaping habit, dry coils burn which is no fun. (these coils are typically good for 60mls of juice or 1 1/2-2 weeks before needing to be replaced)
2. Flooded coils- The heat generated by the coil thins out our juice as we vape causing the coil to become flooded as we vape on it. Too much juice in a coil isn't fun, the excess runs down and out of the airflow at the bottom of the coil (and tank), simply the coil isn't able to burn off the excess juice being pulled into it. (Drain juice out of tank, remove coil, wash tank and base, dry with napkin, wrap another napkin around coil, blow out the coil into the napkin 4 or 5 times to push the excess juice from coil and into the napkin, reinstall, should be good for a bit but flooding will likely reoccur with 50/50 juices)
3. Spit back- Spit back is juice being pulled into your mouth, thinner ratio juices pop more on the sub ohm coils, we want to vape the juice not drink it, though a little spit back will always happen for any tank or device. (more likely to happen with flooded coils)
All coils break in at 3.7 volts, different resistance coils require different wattage settings to equate to the 3.7 volts. Always run them at that equivalent for the first hour to properly break in the coil, then slowly increase the wattage to desired level, increments of 5 work best
example
.5 requires about 23-25 watts to get 3.7 volts
puff on tank off and on for an hour
take watts up to 27-30 for 15 min or so to increase vapor production and get a solid hit
puff and desire more vapor/power? increase again by 5.
And remember to prime your coil well before vaping on it.
Now then below i believe is your issue-
Sitting tanks accumulate moisture from the air (rda's do as well) resulting in a loud crackling sound when initially vaping and typically passes after 5-10 hits. The hit is often not pleasant and can be harsh and stale. The higher the vg the less this occurs in my experience, or the easier it is. Shoot for running a 70/30 VG/PG ratio liquid for that tank (really all subtanks). Also the higher the vg the smoother the vape. Higher pg or thinner juices often have more of a "throat" hit to them. Increased airflow delivers more nicotine to the lungs with each inhale so on a subtank a 50/50 at a 12 feels more like an 18. Thicker juices don't have such a drastic increase in throat hit, or any really at a 3 or a 6, even a 12 is easier with thicker juices though I don't recommend that much nicotine.
Hope this all helps.