I think between your comments and the other archive stories you point to that does clarify and explain the differences with Benn and fills in much of the detail. I like many others of my age on the left hove warm memories of Tony Benn because he was one of the few people arguing for socialism who had a public platform and used it. I feel that coloured some of my response to your obit. Now looking back I think what you said is fair and right. There is more to be said but I don't think you can say it all in one obit.
I think he was a tireless, charismatic and eloquent tribune of the "mainstream" left in decline. However what the left needed was not a tribune but a transformative struggle and hard truths .
The kind of left of the Peoples Assembly the Labour Left, the Unions or a left unity, much like liberalism before it, is expressed as a series of causes or stock ideas whose roots or purpose is not interrogated or analysed. George Dangerfield described 19th century liberalism as an "easy burden to bear" as it was a assemblage of attitudes and assumptions transmitted from the past. The assemblage of causes Greek Independence, Free Trade, temperance, the strange mixture of pacifism, interventionism and isolationism would sit unquestioned as part of the complacent liberals world view.
Today on the left support for Cuba, the morning star or Sinn Fein is almost the same thing. In Unite we keep being told Len McClusky is a "left" General Secretary. In the NUT Christine Blower is argued to be the same. If you ask why its often to do with support for the Miami 5 or UAF. Whether McClusky or Blower actually think much of the Cuban Regime or Love Music Hate Racism (and the evidence to suggest both are not that keen personally) that is what you do to be "left".
Benn's great gift was to encourage people to join the left, however he was never going to tell them the true state of the movement they are joining and the task needed to change it.