Priority group and least connection.

Hi, source address persistency is not a good idea if all traffic comes from a single IP address. 

What is your expected scenario? Why do you think you will need persistency?

If there is a persistency record in the table, F5 basically bypasses load balancing decision and forwards the packet to the member bound to the record. This does not really change much in your scenario since PG2 already only contains one member. 

When Member A has reached full capacity and a new client connection is received before persistency record expires, I believe LTM will try to forward this connection to Member A and you will hit a LB_FAILED condition.

You can see in vs and pool statistics if there is any failed LB or resets, or script an iRule that logs a message when this condition is met.