You wont notice the difference after blitz as far as gunner stats. That is if they are atleast somewhat BVE or completely crap. The only thing I would advise you against is using the yellow starter sailors since it will be locked to your account forever.
My gunners are 10/10 for KM and have been no different then elites for a long time. The only really good thing about having better stats on gunners is that when you get to a certain point you will be able to take a significant amounts of crew off without losing ability. So the better the stats, the more you can take off without noticing.