Are you confident it would actually slice through? The stuff is so ropey that when we run over with the 750a discs it does struggle to cut through it.
I never got the chance to try the leading disc this autumn. I chopped a field ready but it started raining & never stopped long enough for it to dry out enough to drill the cover crop. My drill has the stone release kit & the entire weight of the unit on them once the wheels are lifting up so I'd bet it has more downward pressure than a 750A. I'll see what pressure is wise in the rams though - hitting a big sand stone could be messy...
If it hair pins straw into the slot the coulter tine should sweep it out of the way. If not I'll run the Carrier over it with the discs fully down to loosen the top & hope that slop goes through the drill. Hopefully I'll have a newer combine with a better chopper next summer. Leaving the stubble longer will help but it depends on the brackling as to cutting height. Baling straw is such a ball ache when it rains all of August! Every year we lose 2-3 weeks to rain over here. This time it rained on average every other day from the start of harvest to the end!