It seems like EP Weichs are lighter tension than Spiro Weichs but maybe not. It could be that they are more flexible rather than lower tension. I'm not sure.
I didn't like the sound of the EP regular through the Full Circle in my rig on that bass, it was plastic sounding and uneven, the Weich EP through the same rig sounded pretty huge...way way better. I still prefer the front end of the note and steel sound of spirocores but the full thick sound of the EP weichs was very compelling. I could easily play like that and not want something else.
I can also see why Gamut D/G sound so good on top of those strings, especially amplified. That would be a very big sounding mix where the G string pings out in the upper register and the E string rattles the room beneath.
Not spirocores, different, bigger, warmer but not as defined or articulate. Closer to gut than spiros.