In my view, PoW & PoS is most secure, but feel free to discuss, I might be wrong.
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This is unclear to me, in general I agree, however, I've lost value on PoW/PoS coins that were abandoned from hacking and technical issues. Doing PoW and PoS adds additional complexity that can lead to problems. (Anyone else lost value on Cinnamoncoin?) Additionally, PoW mining seems to cause more issues with block chain forks than PoS in my experience.
Pure PoS coins do have the weakness you pointed out but I believe there are workarounds to fix many of the issues such as a block reward cap and limits on coin weight. I think the barrier to entry where people are required to purchase coins to get started is perhaps the biggest drawback but based on the giving nature of this community so far, I doubt that will become an issue.
Today August 13 is earth overshoot day where humanity's annual demand for goods and services exceeds what the Earth's ecosystems can renew in a year. My guess is that a pure PoS coin is the best way to move value around globe based purely on environmental concerns, with XMG's current scheme a close second. (It seems better than moving gold around, based on the recent spill of toxic waste into the Colorado rivers)
The way things are setup now works very well and I have faith that your capable of releasing another such update based on PoW/PoS technology that functions correctly as well if that ends up being done - so whatever is best shall be.