To be clear, Unshattered really doesn't reduce your total growth by that much, especially in the long term when you have powers beyond Accretion. You're basically only losing the ability to go from "High Expert" to "Master+" in Accretion at a faster rate, and some theoretical high end effects that other systems can certainly eventually replicate. And the loss of your eye and limb are pretty much just cosmetic in even the medium term if you put in a modicum of effort.
A small price to pay for safety and the power to seize the day! What if there's another cool magic system you encounter but are unable to focus on it because you have to spend your resources on Accretion!?
Losing advancement speed sucks, though. Power compounds power, but by the same token advancement compounds advancement. Better rewards from Hunger mean more power which translates to better kills means better rewards etc.
Lets talk hypothetical. Lets make following assumptions:
1) We know we lose 400% advancement speed from To Shatter Heaven, and additional unknown amount from Accretion. Let's say that's total of 500% advancement speed, because that's an easy number to use
2) Let's say that our current power level is 10, and that Unbroken puts us at 100 000.
3) Let's say that each Hunger proc doubles our powerlevel base
After four Hunger procs:
Now: 10*2*5 > 100*2*5 > 1000*2*5 > 10000*2*5 > 100000
Unshattered: 100000*2 > 200000*2 > 400000*2 > 800000*2 > 1600000
Power compounds upon power and thus Unshattered had far greater absolute growth; and yet it's relative growth is virtually insignificant compared to what we have right now. It does heal us mentally, it does help us level up Gisena and it is safe, but it costs us our exponential growth. Those 400% matter a lot due to how Hunger works.
Ultimately, Unshattered shifts risk from now to later; however, I don't feel the need to mitigate risk now, and would rather deal with moderate to high risk now rather than dealing with more risk later on.
