I personally don't think the 45/46/47 should become Xlines but even before they were made non-stop between Newcastle and Metrocentre, they took broadly the same time end-to-end than the X70/X71 give or take a few minutes.

Once they're out of the estates, they follow the same road all the way to Swalwell Roundabout. It's quicker than people think.

It's a pity they couldn't connect the X31 and X70/X71 together in Newcastle without either a ~15 minute layover in Newcastle or two buses following eachother from Newcastle to Sunniside if they were to swap the X30 and X31 departure times around.