a) Miners are very picky about pools, if something is wrong they switch. This is not "in theory", it happens all the time. Do you remember Ghash.io from last summer? Where are they now?
b) PoS has a huge image problem and it's unproven on a large scale.
A) I dunno, haven't mined BTC since before ASICs came out and difficulty and electricity costs skyrocketed.
B) PoS has image problem? PoSV is the solution. Reddcoin is a PoSV coin that gains coin-age over time, but slows down tremendously if the coins aren't moved. Basically, the more you spend, the more you earn. Roughly 5% "inflation" on your coins. Easy to get and there are different wallets available, such as the Browser wallet for google chrome (uses a seed), the typical QT wallet, and the Social Wallet that is connected to twitter, the IRC channel, etc... plus a few new features yet to be seen in cryptocurrencies, are going to make this a breakout coin. Best part: I can stake on a raspberry pi. No spending stupid amounts of money on ASICs that will be useless in a month, no driving down the price because of selloffs to pay for electricity for those ASICs. 5 watts of power to secure the network, not a few megawatts. Plus, I'll actually break even. I don't know one person that has purchases an ASIC recently that has made their money back. Early adopters of the ASICs that didn't buy from BFL might have had a chance, or those who sodl when BTC was > $1200 made their money back, but anyone who's purchased anything to mine BTC using BTC will never make that back. Better to buy BTC or sell shovels.