I had an S2a outfit for years, with 40mm, 50mm, 75mm, 100mm, 135mm, 180mm (?), 250mm (?), and a 300mm lens. Not sure on exact focal length for the 180mm and 250mm. I captured a many good images with the outfit. I finally sold it because I was no longer able to focus on the ground glass. I wasn't able to find diopter corrections, like for an RB system.
Here are some points worth mentioning:
> Given it's focal plane shutter, it's relatively easy to adapt other lenses to the body. (Like, barrel lenses.) Inside the bayonet mount are threads that would make it possible to attach a lensboard. In fact, at least one of the adjustable macro attachments (maybe both?) can have a lens attached to it and still be focused at infinity. This is because one removes the helical to attach the accessory macro bellows. This bellows accessory also have the threads inside the bayonet. This was one of the only cameras that could focus at infinity with lenses attached to the macro accessory. (Perhaps the only medium format camera to . . . )
> The camera has a 1/40th sec sync speed. For this reason, even aside from it's weight, I considered it a tripod camera for photographing stills Though one might have the camera set to 1/250th sec, any movement while taking a photo could result in distortion. The same is true of a Rollie SL66.
> I would rather have an S2a, versus an EC. The EC has a "double" mirror mechanism, where half of it goes one way, and the other half goes another during an exposure. As I understand it, this mechanism was well-known for going out of alignment. It's easy enough to have proper seals for an S2a viewfinder. Not so easy to keep an EC in proper alignment.
> The Nikon 40mm and 50mm lenses were prone to flare. While maybe not as sharp, Bronica made f2.8 40mm and 50mm lenses that were smaller and less prone to flare. (Not as much glass.) Both were multi-coated. Very few of the S series Bronica lenses were multi-coated.
> A minor pet peeve, it's hard to find a straight edge one can use to level the camera.
My current medium format cameras (RB67, Mamiya Press, 6x9 view camera) all have between the lens shutters and can truly stop movement in the proper way. (At fast shutter speeds.) Still, all in all, I really enjoyed using that Bronica system.