If this missile is really solid fuel missile, Chinese DF-41 three stage solid fuel ballistic missile with 2m diameter, ~15 (?) m length and 10000-12000 km range is most similar missile to KN-08
I disagree greatly with that assertion. The DF-41 has not yet been fully supplied to China's military. Furthermore, China's military has over 50+ years experience in ballistic missile technology. The DF-41 represents the latest in China's ICBM inventory.
Iran is following in line with what an advancing ballistic missile program looks like the transition from a Shahab-3 liquid fuel to a Sejill-2 solid fuel. You don't just go from producing a No-Dong liquid fuel to a ICBM solid fuel. It doesn't work that way, not even China with all its resources was able to accomplish that. So it is highly unlikely for North Korea to accomplish building an a solid fuel ICBM after struggling with liquid fuel technology. It simply cannot "skip" to that level of progression and advancement.
Please look at China's advancement in ballistic missile technology to understandhttp://en.wikipedia.org/wiki/Dongfeng_(missile)
The 'number of stages' is not an absolute measure of 'advancement'. Generally, for the same range, the less number of stages the more advanced the program. In that context alone (and there are others as well), Iran's rocketry is more advanced. There was significant surprise by 'experts' when it was determined the first Safir was only two stages rather than what was deemed as a less advanced three stage ('off the self stacked') vehicle. Extrapolating, Iran's upcoming three stage systems will be measurably far ahead of and more powerful than NKs.
This is correct. The fact that Iran was using a two-stage Safir is what led experts to believe that Iran is not only more advanced than North Korea in ballistic missile technology, but also advancing in line with as a country that has an advanced space program.
To put it into context China's first IRBM was a SINGLE stage DF-3. And its first ICBM was a TWO STAGE DF-5.
So once again more stages does not equal greater advancement, it actually can illustrate the opposite.