The above is, with all due respect, incoherent.
The SWP's position is precisely that having minorities represented on leading bodies will in all likelihood lead to those bodies being paralysed by factionalism or obstruction by the minority. Further and just as significantly, the SWP's position is precisely that organised minorities shouldn't be able to exist at all in the party outside of a ludicrously circumscribed "pre-conference period". I'm not misrepresenting anything here and if you disagree with the SWP view on this you should make yourself clear.
You seem to think that "unity in action" requires ending the "freedom of discussion" after a couple of months. You have a brief debate, in which people opposed to the existing leadership are hamstrung by the short time allotted. Then you have a vote, and then the losing side shuts up for a year. That was not how the Bolsheviks understood democratic centralism. They would have a discussion and a vote and then carry out the majority decision, but it would never have occurred to them that this meant that the minority weren't entitled to keep organising for their views and keep arguing for them, even as they worked to implement the majority line. This didn't stop them from growing on a much greater scale than the SWP have managed and, for that matter, it didn't stop them from playing a rather significant role in a Revolution.
The SWP's version of democratic centralism - the version where there is no "freedom of discussion" for three quarters of the year - is unique to it. It is very different from the approach used both by other Trotskyist organisations today and by the Bolsheviks, the model it is allegedly based on and justified by reference to.
In a later post you argue that it has somehow been uniquely successful, I can see on the sole evidence that the SWP is, not even by very much, currently the largest far left organisation in Britain. This is bizarre on every level. If we were having this debate in 1975 would you telling me that Healy's approach to internal debate was clearly the best? If the Socialist Party overtakes the SWP again, will you be telling me that I'm right? How about here in Ireland, where the Socialist Party is larger, is it correct to allow minorities to organise here, but not in England?