Funny you should say that, Wombat, having apparently just experienced first-hand the main problem with using solids on herd-animals. There are a great many Northern Territory locals, myself included, who routinely kill big buffalo bulls with Woodleigh softs without incident: have been for decades. I've personally never needed to fire a solid at a buff, but sometimes carry them in case an opportunity should arise.
It never does!

Congrats on your trophy bulls though, mate. Sure, its hot at the moment, bloody hot, but October/November is my favourite time of year for hunting in Australia's Top End. Planned your next trip yet?