Back when they came out, I think the only soft balls out there were solid rubber and liquid center wound balata. I was only a kid then so I'm trying to remember. Tons of 2 piece surlyn distance balls that were the rage...Titleist DT, Top Flites, Pinnacles.
The only thing that felt soft off of a set of regular cavity back cast irons were the rubber and Titleist Balatas. Becu gave a noticeably softer feel when hitting the 2 piece balls....long time ago
So, back then, better feel with becu because of less ball composition choices. Now, so many softer ball choices, all clubs feel like Becu. Just a cult classic now....