Having read more articles and publications on POS and attacks, and listening to input here, I really can't offer a better solution than no consecutive POS blocks.
Knowing POS exists as a wey to secure the blockchain with less electricity waste may not be as critical to YACoin as it is to other coins. With a higher N, the power consumption on my cards is lower (comparing YAC to LTC or any other N=9 Scrypt coin). This may drop even further i the future. If disallowing consecutive POS blocks now keeps YAC from imploding, I say we have to do it. This may be a case of kicking the can down the road, but the only other solution we've seen implemented is centralization of the blockchain.
One question I still have is : what is to prevent a user from forcing the generation of a POS block (which is just a flag when starting the wallet now, correct?), jumping offline before the generation is complete and coming back on 6 hours later. Does it attach to the end of the blockchain? or does it insert where the blockchain was when the block was generated (not submitted), potentially orphaning 360 blocks?
If anyone has any good references on the subject, I'd love to read them. I've read
https://en.bitcoin.it/wiki/Proof_of_Stakehttp://bitcoinmagazine.com/6528/http://www.peercointalk.org/index.php?topic=936.0http://www.peercointalk.org/index.php?topic=809.0http://www.peercointalk.org/index.php?topic=979.0