Remember we are not there to assess the referee any more, we are there to observe, and the FA are very clear that the emphasis should be on coaching that referee to help him achieve the next level rather than finding faults to prevent them getting there. Although I suspect the newer generation of assessors, now observers, have seen it that way for ages any way.
I would personally welcome a referee speaking to me about this before the game, as long as it is done in the right way. If he said "do you mind if I don't bother checking the player's kit" I wouldn't be impressed, whereas if he said "I've done the checks and I'm struggling with undershorts as the away team have three different colours of shorts", or "the away keeper is wearing black but he has nothing to change into that doesn't clash with the two teams" I would offer him guidance as he has shown initiative. Obviously I would tell him to report it to the league after, but the emphasis at that level should always be to get the game played.
I would personally welcome a referee speaking to me about this before the game, as long as it is done in the right way. If he said "do you mind if I don't bother checking the player's kit" I wouldn't be impressed, whereas if he said "I've done the checks and I'm struggling with undershorts as the away team have three different colours of shorts", or "the away keeper is wearing black but he has nothing to change into that doesn't clash with the two teams" I would offer him guidance as he has shown initiative. Obviously I would tell him to report it to the league after, but the emphasis at that level should always be to get the game played.