Thoughts about adding subwoofers?

I've got an old Yamaha YST-SW320 which has a 10" downward firing speaker, active servo tech, and puts out 250W and weights in at 18kg. It's putting out the bass just as well as it did in 2001 when it was new. Its a pretty good sub for a living room setup and rattles the walls and doors in that low 30Hz or less range. It hides beside a sofa the sits on the right hand wall in a relatively small room.

I would be especially interested in knowing how people that have added a sub in a living room home theatre setup feel after running another sub for a time. Was it worthwhile?

I'm wondering how something like the SVS PB-2000 sub would pair with this? Do I really need to worry about matching subs? Is it a thing? I assume I'll place them diagonally opposite one another, angled to avoid standing waves.

BTW, not my gear in the pic, its just a pic of the subwoofer. I've got 5.1.2 and elac speakers, with Energy rears.

EDIT: Thanks. I'll see if anyone's got an option to try before I buy. If not I'll probably stick with the single sub for the foreseeable future.