It all depends on how you define overpowered anyway. Sure, Blood Magic and Rotarycraft give you some insanely powerful stuff, but when you put that against the context of the sheer amount of blood you need to pump into Blood Magic (which there is no convenient way around - even with crossmod exploitation to provide insane regen, it's still a heavy time investment) or the power requirements in Rotarycraft, it looks more reasonable.
For me, something is overpowered if the time and resources you have to invest into it feels cheap for what it can do. I'd point to Geostrata as an example of this - the crystals you find in caves are capable of dropping 4 shards even without any fortune on your pick, and then all you need is 2 obsidian, 9 gold, 9 redstone dust and 4 glowstone dust and you have something which gives you 5 minutes of a tier 3 buff. I've never upgraded to a pendant from there, because the potion crystals are more than powerful enough as is.
Compare that to what you have to do to get Bedrock Equipment in Rotarycraft, or Bound Armour in Blood Magic.