I will focus my response continuing the discussion on the relationship between strategy and tactics, in regards to Allende and otherwise.
In the revolutions we have studied, it seems as though practical considerations often induce tension into the relationship between tactics and strategy. Generally, a revolutionary force begins as a small fraction of a population without the capacity to unilaterally implement its strategy. In some cases, the violent power of these small groups grows without compromise to the point that they can overthrow the state and implement their original strategy, but I would say these cases are rare. In many violent revolutions, original groups often employ tactics to increase broader support or create bridges in revolutionary groups that involve making concessions and in some ways changing their broader objective (read: strategy). In nonviolent revolutions, these concessions are even more common as the revolutionary force has to win over an even larger section of the population through its ideas.
This brings us to Allende. As was highlighted in his discourse with Debray, The concern of conciliation and ultimate obscuring of the original strategy is of high concern of many Marxists looking for their conception of a total revolution. The reliance on electoral means almost necessitates this kind of bargaining, unless the electoral population is unilaterally behind your cause and can champion it democratically. To some extent, Allende tries to claim that this is actually true in his case as all of his powers and leanings are ostensibly derived from the workers (although he contradicts himself later by postulating that they may need guidance). In reality, I think these concerns are valid, and in reality, Allende did end up becoming pulled into more center through participation in the electoral system, having to negotiate with other branches of government not under his control.
I think a salient argument aside from whether this shift to the center happened or not or is endemic of non-violent electoral participation is whether this shift is an inherently negative one. To push a strategy that is not supported democratically does not seem to be an adequate end goal of a revolution. The main issue, of course, is that often times electoral politics is simply not democratic, and popular ideas are not manifested in executives and legislatures. In the American left movement, this is one of the most widely debated issues. To some, participation in the current political system necessitates operating under certain assumptions and making certain concessions to mainstream Democrat values that some are unwilling to make (the necessity of these concessions are only exacerbated by the first-past-the-post electoral system and the active role the DNC plays in selecting centrist primary candidates). The other wing of the left who like to view themselves as more pragmatic often accuses the more uncompromising side as indulging in a kind of utopian fantasy (to perhaps put it a bit harshly). They choose to highlight the fact that given the relative strength of American democracy, it seems incredibly difficult to influence the state in meaningful extra-electoral ways. In my mind, the kind of non-violent, electoral focused work presents the most effective single path to take in a functioning democracy with a powerful state. Despite accusations of incrementalism from my revolutionary-minded comrades, I still see the current tactic of conciliation as a smaller step to more meaningful strategy of left-wing reform.