Thank you for the information. I will probably go for a second-hand ZenWifi XT8 as I don't want to invest in a full new system and I am happy with the performance.
XT8 is also triband, so if I add the BT10 I would loose the triband (dedicated 5 GHz) for router communications as the BT10 would use the 5GHz band to connect to the XT8 and also for connecting to the electronic equipment ?