Kilroy, moving 4 and turning will use 6 ap (i.e. use two cp), why not turn around next turn? you will still be able to kill the nearest stealer that way.
Warhammer, don't forget to reserve some ap for going on overwatch. assuming we just get 1 cp that means moving to face the stealer and going onto overwatch (which will give you four shots at killing it instead of two). Any CP higher than 2 could be devoted to shooting it this turn, and leaving one cp at the end of the turn to clear a jam.
I've always been a tad leery of overwatch reliance. in my experience, it is better to shoot it now, this turn if it can close to kiling distance rather than letting overwatch handle it.
Mostly, this is because the RNG will cause you to jam in overwatch whenever possible
The issue with just shooting instead of overwatch is that you don't know how many stealers are part of that blip, and where they are positioned. If the blip resolves into more than one stealer, then it's possible that the 2nd stealer will be one square north of the blip pictured above. That stealer would be out of your line of sight and would be able to reach your position in 5 moves, leaving enough time for one melee attack (a normal space marine has a .659 be killed by a single melee attack). So while the RNG might screw you over in overwatch, it may also very well screw you over if you choose to dakka it instead. We have enough cp that you can afford to reserve one to clear a jam, dramatically reducing the chances that your face will be eaten this turn. You don't have a means of assuring the a stealer in cover won't close.
Ultimatly it's your choice, I'm just a voice in your character head right now.