I can only comment on the XLR Element. I picked up a magnesium element. I was going for light weight. I am quite happy with it. Holds the barreled action securely, mags cycle fine, pretty light, nice little add-ons available. Lead time was LONG (between 5 and 6 months I think).
Not cheap!
Will be swapping out the scope at some point. just needed something on it to sight it in and do load testing.