I am by no means the best person to answer this nor do i play a 1Pal 1 Mag 3 Sham combo. I have run 4 Sham 1 Pal combo and it seem to work perfectly fine for me. It has everything i need. On the other hand the Ports, free water, and a CC isnt a bad option also. Just remember, you have a pally that is the AoE tank, and can hold AoE agro. So CL works great for downing multiple mobs at a time. I think the Mage would work fine. imho making 1 macro for your mage to sheep a target isnt that hard. Frost bolt is a 2.5sec cast and is only .5sec off a sham LB.

I say go for it. They are all still ranged caster classes. Just dont let that mage get beet on. Clothie's die quik!