Priority Group Activation, why use it?

I would like to know your opinion, hope you can help me; in the pool list, I have four pools with different names and two members configured in each one of them and all assigned to the same server, same IP but with different ports; the priority group for these four pools are 3 to 1, member 0 is the member with higher priority (3), member 1 is the member with lower priority (1) both members are active.

As per bussiness requirements our customer needs to make the failover between these members leaving only member 1 as the member with higher priority (3) and member 0 as the less (1), my question is, Is it possible have a risk if we make the failover, is it possible have impact on services? Which could be the best option? change the priority between members or disable the member that customer needs? Disabling one of the members failover is in automatic?

Hope you can help me, thanks in advanced for your help.

Regards.