....and you can guess who the voice of dissension was

I always thought it should have been castellan at 40pts, defender at 45pts WITH fleet separation or defender at 50pts with fleet inclusion.
And by that I mean if GW and FW fleets were entirely separate, the point difference would not matter so much. In the original BFG:R documents plaxor did this, and it explains some of his decisions.
If the two were in separate fleets the power difference between the two would be a non-issue. People would go damn the defender is way better and other people would go yeah, your right. Play GW tau if you like it so much.