I want to challenge your assumption that revolutions follow a unilineal evolutionary pathway (from heavy streetfighting to armed urban guerrilla insurgency) and your assumption that the "active stalemate plays into the power of the state".
Urban guerrilla insurgency could refer to a specific strategy of clandestine armed groups, which do exist in Greece, and are a minor but important part of the current struggle. Where such groups have been the main protagonists, the result tends to be total pacification of the struggle, or triumph of a new authoritarian regime.
Another possibility is open civil war. The situation has not yet evolved into an open civil war because most Greeks continue to reproduce the narrative of democracy and its idea of protest and social consensus.
As for your second assumption, yes, they are currently in a stalemate in Greece, and stalemates wear down on the comrades, but on the one hand they benefit from a tradition of heavy street fighting (in other words, that's a status quo beneficial to an anarchist struggle), and their continued "choreography" as you call it undermines the democratic credibility of the regime and limits the possibilities for investment, recuperation, and intensified repression.
Various comrades in and from Greece have opined as to why things have not gone further there. After December, many blamed television.