Lapidus

Greetings Everyone! I have a question regarding speakers in a dedicated basement HT. I would like your valuable opinion about the L C R speakers I should buy. 1. RP 280F or 260 F paired with either RP 440c or 450c, and I know that "Big is always better", but sometimes space etc also needs to be considered. That said, is 260F "enough" considered my room and the rest om my equipment? 2. If I choose 260F over 280F, do I go wrong if I choose 450c instead of 440c? Here is the hard facts: Room: 3,5 meter x 5 meter height 2.2 meter Very well acoustic treated with GIK panels on the walls and treated ceiling. What I have today: Sub 2 x R112SW Surr 2 x RP250s Back 2 x RP240s A/V receiver Onkyo TX NR1007 9 x 180 w 6 ohm 160 w 8 ohm viewing distance: ca 3 meter Best regards Mark