iRule to select pool based on client IP and group data list

Taking IheartF5's thoughts in consideration:

I'm thinking of doing the following.

Put in an iRule to look for the client IP and see if it matches one identified in the test_list for testing purposes. If it does, go to a defined pool.

On the default pool, set priority group activation for the default pool = less then 1, then when the old servers are disabled, the new servers will take over.

Thoughts on the following:

Default pool = the following IP addresses and priorities:

IP1(original server) (Priority group 3)

IP2(original server) (Priority group 3)

IP3(new server) (Priority group 1)

IP4(new server) (Priority group 1)

IP addresses IP3 and IP4 are also in the test_pool. The new servers should not get any traffic sent to them as long as none of the original systems are up. Once both the original systems are down, traffic will go to the new systems.