Heh, the German Greens started out just like that :-) outgoing foreign minister Joschka Fischer was a leading member of the second wave of the extra-parliamentary leftist opposition in Frankfurt am Main, one of those squatters who settled in abadoned old houses estate developers wanted to run down and build something else in their place, and clashed with police. When Joschka became a minister for the first time, in the middle eighties when the first SPD-Greens coalition formed in Hessen state, he was sworn in clad in jeans and wearing a jogging shoe.

As for the current state of the party, I think you are about right, except this is the official line, the one carried on by the now dominant 'Realo' wing, but there still exists a significant "Fundi" wing - those who aren't really pro-market, and have a much stronger focus on the environmental issues. (Also, what you call 'centrist' would count rather strongly to the right in Germany just three decades ago, or even 15 years ago when I lived near Frankfurt.)

Regarding Fischer and Merkel, Fischer on one hand is not a party leader (the party has a double leadership: currently Claudia Roth and Reinhard Bütikofer, the first a Fundi the second a Realo), on the other hand, he must know himself that the aversions of his voters are too big (after all, FDP and CDU campaigned with abolishing just those reforms the Greens achieved in the last 6 years) - I believe hence his public rejection of the Jamaica version.

_{*Lunatic*, n.
One whose delusions are out of fashion.}