While msm2000uk has beaten me to it in alerting you to the distinct possibility of QR swapping aircraft - on four DOH-FRA/MUC or v.v. business class trips last summer I only flew QR's A350 just once out of the four flights scheduled to use that particular type - the one flight on the QR A350 sticks out in my mind as being my most enjoyable flight of 2015 (even more so than my QR A380 J flights). I love the spaciousness and quietness of the A350 cabin and the QR J seats.

You have chosen wisely; I hope you enjoy the QR experience.