Hydro are more of a cup point than flat meplat, and I believe a bit of work went in to getting the meplat the right % of bullet diameter for tissue disruption vs penetration.
From discussions with Geoff the faster the better, so light for calibre at max speed = soft, heavy for calibre at traditional = solid.

Saying that I have a box full of tipped 400g .458s that I should be able to get up to 2100 in my Blaser, but I'm still left pondering if I only want to take 1 load on my next trip for buff I'd be better off with the 325g at 2300. Has anyone here used the Hydros out of a .45/70 on buff?