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A note about the Mekanism Jetpacks they are using
Mekanism: Feature Request Thread | Page 19 | Feed The Beast
It seems that they are all opting for the Mekanism jetpacks in their series' instead of the simply jetpacks option. The issue with this is that The armored version of the mekanism jetpacks are currently broken and don't provide any armor at all even though it puts the indicator on the armor bar. This leaves them very vulnerable and is a big issue as far as taking dungeons goes. You end up taking a lot of damage (espesially from the archers I've found) that should be mitigated. This is seen a lot in the Flux Buddies series with u/Yogscastlalna and u/YogscastKim
What they should be using are Armored Resonant Jetpacks. These are slightly more expensive to build, but they use RF as fuel and their armor is a diamond chestplate's worth of armor an is not broken! I've found this makes you feel much more invincible as you would expect from such an expensive armor item.
Cheers!