As far as I know, 5D's usually has basically the same ratings that the new episodes of GX did over the summer. I personally think that it's too early to compare GX and 5D's as a whole since GX has more episodes than 5D's has. Comparing their first seasons seems to be a fairer comparison. In terms of their first seasons, 5D's has a much better start with actually stablizing a plot. I don't think GX was good at having a central plot until season two. The Shadow Rider arc was really hit or miss after the first two Shadow Raiders.
I doubt that any fans should worry. I don't know if it's different in your area, but 5D's only came on a half-hour earlier for me. That's barely a need to feel nervous at all. Besides that, the main reason why 4KiRAB moved it was so that Kamen Rider would get the last slot. Live-action shows have usually been on the first or last time slot on a 4KiRAB block so I think that's why they did that in this case too.
