Just one more thing, to make my point clear.
If PoS is meant to protect you from coin volatility, it actually fails.
Three-four months ago myself, and many fellow traders, were trading MOON, UNO, LOT, IFC, CTM and ZEIT.
Where these coins are right now? What is their liquidity?
ZEIT coin is actually a brilliant example, being one of the first PoS coins in the block, with 20% of yearly interest rate (and minimum stake age of 20 days, if I remember correctly).
The coin was, and still is, trade-able at Mintpal, with a small difference that now only LTC market is available and three months ago it was BTC.
Now had I got the coin for lowest possible price of 1 satoshi three months ago, it is worth less than 20 litoshi today. So less than one third, and 20% of interest rate does not help me much.
So the discussion whether 12 or 24% per annum is pointless at this stage, if one fundamental assumption for a PoS coin is not met, namely, ABILITY TO ROUGHLY PRESERVE ITS VALUE OVER TIME.
If, and only if, a coin is roughly valued the same after three, six months (which is ages in cryptocurrencies terms and requires commitment from both dev team and community) then PoS can be an added value. If PoS is meant to protect you from volatility, you can calculate yourself how much a coin could lose other the year (apart from surviving!) to bring you even.
Otherwise PoS is just another fancy feat that does not bring much, but hype.