I haven't tested this recently, but the last time I did, I was about 3 stones stronger on slow games on IGS. On KGS it was about the same either way. Go figure.
I think it's not just about you. It's about the population of opponents. Some people only play fast and some only slow. It could be that on some servers the stronger players play faster games whereas on others they play slower.
As I recall, what I concluded was that on IGS, my level of play deteriorated in faster games. More mistakes, more misreads, more time losses. But my opponents did not seem affected by this.
On KGS, in faster games, my play deteriorated in faster games. More mistakes, more misreads, more time losses. But I was still okay because the blitz players played such terrible openings that it was like I started with a handicap, so it evened out.
On Tygem and WBaduk, players just seem to play fast regardless of the limits, and I sometimes fall into the bad habit of getting caught up in their pace. But I haven't played there consistently enough to know what may stable rating would be (assuming it would even stabilize.)
For me, there's a threshold somewhere, and if I play faster than that, everything falls apart. It may have to do with whether I have time to estimate the score. Anyway, I'm very aware of when this is happening, so I don't feel the need to dwell on it.
Many high dans (Aguilar, Shikshin, etc.) have mentioned that they really need tournaments and IRL play to improve. It could that even if they can muster the discipline to take online games seriously, there is no way to get their opponents to do the same. There is something lost in not being able to get your opponent's best game, I guess. IRL games don't solve it completely (there are go clubs that meet in pubs, after all
), but maybe the problem is lessened.
). So I have a feeling that the FICS rating systems are not going to provide us too much fuel for a reasoned discussion. 