Back in the early 1970s I went to hear a panel discussion between three rabbis, one Orthodox, one Reform and one Conservative. I no longer remember who the rabbis were, so let's just identify them as Rabbi X (O), Rabbi Y (C) and Rabbi Z (R).
The purpose of the panel was to discuss where there might be agreement between the movements, where there are disagreements as might be illustrated by an examination of certain issues. Forty + years later I have very little memory of what was actually discussed, except for the issue of the agunah. What has stayed with me all these years is how Rabbi Y would address his fellows as Rabbi X and Rabbi Z, Rabbi Z would, in turn, address the others as Rabbi X and Rabbi Y, but Rabbi X made a point of addressing the other two rabbis as Mr. Y and Mr. Z.
I had planned a rather different look at some the issue raised in the first part of your post. However, I don't know if there is any point. With this anecdote in mind, and noting Tumah's position, as well as CMike's ongoing disparagements, and without any input from rosends, I just don't see, at least for the forseeable future, the non-Orthodox and the Orthodox working together to hammer out the conversion conundrum. I do find it highly more likely that the major non-Orthodox movements can come together on this issue, although I can see where there might be some bumps along the way