Further to what I posted with video above - right is a standard rope access cowstail, left is tied with a BIG overhand knot instead. I'm wondering if left gives better shock absorption?
Personally I don't think left is any more bulky than right. Left is a stronger knot (but right is strong enough). See also my notes above on other advantages / disadvantages. I'm pretty sure that repeated drop tests will give lower (better) results for left than right, as there is more knot available to absorb the load, but I'm not sure whether it'll make any (significant) difference on the first test - probably not on shorter drops, but it may on longer - which is what you want...
Both are tied on a suitable rope length for a standard cowstail, rather than these, so longs aren't long enough, but it was just 2 bits I had the same length & the knots used up pretty much the same amount in both.