Just my opinion,but I have been flying competition F3A for a long time now.....
Obviously it's ideal to have absolutely equal movements on separate elevator halves, but as long as they're close(say within 1.5mm in each direction),I seriously doubt if many flyers would ever be able to tell,or demonstrate, any flying discrepancies.
And,most importantly, total loss of elevator function, is the one flying control that is virtually certain to result in a written-off model-if you lose one half you'll be surprised how little rolling effect it has-it just reduces the pitching power available.