I travel regularly with an old Polycarbonate cabin plus. It fits in E170/190. Unfortunately that model is discontinued and the currently available Polycarbonate cabin plus version with the "sleeve" outside is marginally thicker and I suspect it might be therefore thicker than the 25cm claimed by rimowa.
I took a metal one aboard one time, when unexpectedly switching from lhr to lcy. It fitted (ultra tight) only one side (left hand side?) but not above row 2,I had to put it above about row 5.The width was right on the limit so you had to bend the lid a bit to close it.
I would therefore say No. Cabin is fine on BA.