So, let us take a look at my analysis and predictions.*
I. General traits
a. Extreme polarization
b. Abandonment of procedural norms
c. Frequent use of
i. Political violence
ii. Private or partisan paramilitaries
a. Failure to understand
i. Normality of opposing parties
ii. Concept of a loyal opposition
b. Right wing (major category)
i. Driven by fear
1. Elite fear of reforms threatening power
2. Middle class fear of displacement from below
ii. Failure to distinguish between radical and moderate reformers
iii. Middle class in danger of being squeezed out
iv. Most common triggers
1. Economic crisis (major category)
2. Past or present loss of a war (minor category)
v. Not usually dependent on a charismatic leader
c. Left wing (minor category)
i. Democratic forms mask a cozy oligarchy
1. Polarization between rich and poor
2. Middle class usually weak
ii. Driven by ambition
1. Of leader for power
2. Of people for a better life
iii. Dependent on a charismatic leader
iv. Triggers unknown
v. Most likely to succeed if it follows broad historic trends
III. Ways to fail
a. Election and subversion from within
b. Military coup
c. Civil war
d. Foreign invasion
Extreme polarization: Yes, the dictatorship appears to have arisen out of intense factional strife between the People of the Plains, the People of the Coast and the People of the Hills. The ancients (with no prompting from Marx), interpreted this as class struggle between rich and poor. Many modern historians also analyze it in terms of regional or kinship rivalry. But regardless, the dictatorship clearly arose out of factional strife that no one else seemed able to control.
Abandonment of procedural norms:Hard to say, since we don't know what the procedural norms of the time were. But Aristotle mentions two years in which no archon was appointed and one archon who unconstitutionally overstayed his term until he was removed by force, so yes, this does seem likely.
Frequent use of political violence and private or partisan paramilitaries:Pisistratus did this, both with his club-wielding bodyguard and his foreign mercenaries. No one mentions the use of political violence or paramilitaries by anyone else. Does Pisistratus' act of wounding himself, claiming to have been attacked and calling for a bodyguard show that his accusations were credible, or that his paramilitary was something unprecedented? Probably both.
I predicted that the danger would more often be on the right than the left and more often be driven by fear than ambition. In fact, I identified fear with the right and ambition with the left. But how to make the distinction? When people feel close to losing what they have, that is fear. When they want something they never had, that is ambition. But what if people have lost something and want it back? Is that fear or ambition? Here, the old nobility appears to have lost its preeminence and wanted it back and perhaps feared losing more. Creditors had seen debts to them cancelled and wanted to be paid. Citizens with flawed pedigrees feared being found out. Aristotle lists all of these except the old nobility as followers of Pisistratus. There is no sign of a middle class that feared being squeezed out.
The old elite had already seen its power undercut by radical reforms. Certainly no lost war triggered the dictatorship; to the contrary, Pisistratus seems to have been one of those victorious generals later generations saw as dangerous. Any talk of an economic crisis is speculative.
Democratic forms mask a cozy oligarchy with a weak middle class: Due to the sparseness of the evidence, it is hard to tell. However, Solon had given the poor the right to vote and to serve on juries, but not to hold office. Rural dwellers (probably) found participation a greater hardship than it was worth. So far as we can tell, gaps between rich and poor were growing and no middle class is mentioned. Certainly the Plains faction is said to have wanted an oligarchy. And most to the point, the old nobility was not going to give up its power easily. It was the dictatorship that broke it.
Driven by ambition: Athens was rife with ambition at the time. Peasants were ambitious to get their hands on land. The commercial classes were ambitious to be recognized as equal to the old nobility. And, of course, Pisistratus was ambitious for power. It proved the perfect combination.
Charismatic leader: I am assuming that Pisistratus was charismatic, based mostly on his ability to organize a previously passive and unorganized population, and his theatrical gestures. Certainly, he was a strong leader aiming for personal dictatorship. He was also a type of charismatic leader that our own Founding Fathers greatly feared, a kind that was the undoing of the Roman Republic -- the victorious general, who parlayed his military victories and his personal charisma into dictatorial power.
Triggers: While right wing threats usually come from economic crisis, lost war, or the memory of a lost war, I was not sure what triggers the threat from the left. In fact, it is still hard to tell. Obviously something was triggering the change, because similar dictators were arising all over Greece at the time. So far as I can tell, it was simply the ambition of the rising commercial and middle classes for a share of power, and ambitious leaders eager to give that desire form.
Historic trends: I am not really sure if this belongs here, but people who want a better life by turning the clock back are less likely to succeed than ones who want a better life by pushing it forward. The tyrannoi across Greece at the time were pushing it forward. The proof (I suppose) is that so many arose and then vanished at about the same time.
Ways to fail:
I suggested subversion from within, military coup, civil war, and military defeat, while leaving open the way for others. Pisistratus twice attempted a military coup and twice saw it fall apart. He finally took power in a way I did not foresee -- by hiring a foreign mercenary army. I guess that's easier to do if you live in a bunch of city states all next to each other and eager to subvert each other. Still unanswered -- whether these various forms of failure follow predictable patterns.
*I have modified a few, but mostly for the sake of clarity, not substantive change.