You ask great questions, let's see if these few thoughts may be of some aid in your decision-making: 
- A school's goal is typically NOT to identify a person as gifted, but rather to make a match between available levels of educational challenge and the needs of the pupil.
- Schools typically differ in their gifted-challenge-level educational offerings (if any).  Therefore when changing schools, a student's placement may differ.  
- What did the prior school offer/provide as their gifted-level ELA program? 
- What does the current school offer/provide as their gifted-level ELA program? 
- Does the current school's offering for mainstream ELA more closely resemble the prior school's offering for gifted-level ELA?
- How close were your child's scores to the cut-off for the current school's qualification for gifted-level ELA? 
These old posts may also be of interest: 
1) Meeting a student's need for academic challenge - 
http://giftedissues.davidsongifted....Re_what_kids_don_t_learn.html#Post2330622) Meeting a student's need for intellectual peers - 
http://giftedissues.davidsongifted....icle_about_poor_school_f.html#Post2296043) Crowd-sourced tips for parental advocacy to meet their student's educational needs - 
http://giftedissues.davidsongifted....y_Advocacy_as_a_Non_Newt.html#Post183916