A 100S has a JBL D130F and a compression driver, and I think was discontinued by 1970. Sunn is basically divided by era of ownership, Sundholm inception-1971, Hartzell 1971-1985ish, and Fender 1985ish - end.
The gear had decidedly different characteristics, yet shared some crossover/re-issue models and gets a little confusing, if you spend some time with the catalog thread stickied in "Q&A" you can get a feel for what is what.
As far as your search for a bass cab, I don't think any Sunn 2X15 sounds bad although people have their personal tastes and preferences.
Do some searching around here and you'll pick up a ton of knowledge about Sunn.