The 440 source girdle is EXACTLY the same as what you get from Hughes (unless a recent design change was implemented). Pretty sure they get them from the same source, and use the exact same ARP stud part numbers.

Thickness has no bearing on the effect of the girdle, as it's intention is to eliminate "flag-pole" esk wiggle of the main studs, which attribute to cap walk and reverberation through the block eventually leading to cracks. It is NOT designed to influence lateral twisting of the block itself.

My girdle completely eliminated my capwalk issue, which I have photos of the proof.

The BCR kit is on a completely different level, but, IMO, not worth the machining costs to face the pan rail and the caps to tie everything together. I utilize his aluminum caps with my 440 source/Hughes style girdle and an very happy with that set-up so far.