Ok here is the thing. I tried it out this afternoon with my series I and barefaced cab after I moved the internal trim jumper lead to 20db.
Previously I had been using the input jack socket at the rear to connect my bass and found that was good but a little quiet volume wise compared to me using the F1-x, but after an on line conversation with Will Gunn he said thathe thinks the jumper inside relate to the jack on the front and he uses it as it came from alembic. So when I took it to rehearsal and tried it out, the result was a massive output which seems to be hitting the power amp too hard and distorting so it was back to the rear jack input which was fine for quality but not enough volume I think for a larger stage/venue.
I do think it would be great for reggae but for other things where I need to make quick changes on the bass, having two sets of filtering, one on the bass and the other on the SF-2 I would find quite confusing as the SF-2 seems more in charge than my bass.
So on a first outing I think my next test will be drop the jumper in the SF-2 back to 10 db and try it out by putting my bass into the front jack and see what affect that has on things. My ears tell me at the moment that the SF-2 is more effective in the send and return loop of the F1-x than on it's own. But we shall see.