This is a great idea Chris and I 100% agree. Right now, custom reports offer only the measurements that all checks offer, so all those great stats with collect in RBC aren’t available. We are fixing that. First step is we are about to introduce a bunch of additional RBC metrics we collect. Then we are revamping Custom Reports so that RBC checks can include more metrics, like DomContentLoaded, etcDavid Fye commented
This is something we definitely need. We have a "long tail" of scripts that run post DOM render and the numbers we get from Page Loaded do not reflect the actual user experience.
This would be of great help, please add these metrics.