I will be going for the axe/shield combo, as I think that it really isn't worth using an X points model, when it can easily be killed by the krak missiles/melta guns/plasma guns/ whatever other high strength low ap weapon that in in almost every marine squad.
It will also help when facing dedicated CC units, as they often will be able to take down several of the wraith blades quite easily, or even a power fist sergeant/ork nob with claw, you will be unable to challenge them out (unless there is a HQ that can deal with them) due to the lack of characters in the unit, so they will be free to wreak havoc if they survive your blows to strike.
This is especially the case if you are footslogging them, as they will have to face these missiles as they footslog across the entire board. I suppose you could add a spirit seer with conceal to the unit, and then run from cover to cover, giving you a better chance of surviving than the shield, but it will slow you down.