If you have a look at the code, you would understand everything what 400% means. Actually, CoinHunter is just promoting for solidcoin. I think CoinHunter is also an excellent programmer through the thread. Apart from that, I can't see some other excellent points.
P.S. "400%" is not invented by SolidCoin. Everyone can see this "400%" is there in Bitcoin. What CoinHunter did was that he promoted it as a special feature belonging to SolidCoin.
Yes Bitcoin has a 4x limit on increasing or decreasing. However it is far too long, every 2016 blocks. Bitcoin also desires a "magic number" for it's blocks, and that is 10 minutes. SolidCoin on the other hand tries to stay _UNDER_ 3 minutes. To reduce variance and provide a fast network. As such the people thinking "coin generation goes too fast" are kinda missing the point, it is supposed to go fast, it isn't supposed to always be at 3 minutes and if the system is "gamed" by a miner or two to provide "artificially" higher speeds then that is also "ok".
However I also stress network balance is very important and having SCGuild so powerful on the network (like deepbit is on btc) isn't good, so I'll be looking at ways to solve this going forward, even though I think the current situation will resolve itself soon.
Yes, lowering retargeting period make sense at a certain time range whether it is 3 minutes or 4 minutes.
Variance reduction as you said maybe considered as the absolute variance, however, reduced variance in your retargeting period can't make it more stable from what is happening, which seems to be a
sin(t) function I have said last day. You also realized it as a cycle, which is the stability problem, and at this moment I can't guess whether it will be more stable as time is going.
Sometimes network balance is out of one's control, so we can just improve the algorithm to be more resistant to network unbalance.