Top Law Schools

There are many firms that say "top x% and law review or journal experience preferred" on their hiring criteria.
If I know I wouldn't be in law review/journal at the transfer school, do you think I would be at a significant disadvantage at the new school OCI compared to the current school where I will likely be on the law review and have top 5-10% grades?

In another words, I wasn't sure how much emphasis firms put on journal/law review experience when they hire SA for 2L summer.

My understanding is that it varies amongst firms, but for the majority of firms academic success is most important. However, we would need more info to give a better evaluation of your decision to transfer or not.