I have been using Givi cases for the last 15 years on my Honda CBR-1100XX. They are solid and waterproof. I order a Givi rear rack specifically designed to fit the Yamaha FJR-1300. Then I will just transfer my Givi case to it.

The stock rear rack is just plastic and it was just for look as there is a sticker on it that said "Max load 3 lbs". The Givi rack has a 10 kgs (22 lbs) max load.