No that is not 7.1. You only have 3 center speakers instead of one. The center will be more powerful than with only 1 center. You might experience a bit of odd sound experience as the center is a bit wide. Geoff explained in the video of Henrik of B&O Technik Forum on youtube how you can set up the three speakers in Eclipse in combination with speakers LF and RF, LR and RR.
To have 7.1 you need surround hight speakers. Also be aware that your BL11 is not too powerful and will not give you the full theater experience, therefore you”ll need a BL2/19/14sub.
My guess is the bass management on Eclipse will send the bass to BL17 instead of BL11.