Try it and find out yourself, dont listen to advice regarding this !
Easy to just shorten the rear lines a bit on the leaders, and see how it goes.
Measuring if equal does not make any sense IMO, as we all prefer different trim settings.
Usually in the long run you might want to lengthen the rearlines though, as they get shorter than the frontlines over time - but if you feel you have to sheet to much in, shorten the rearlines and go
I always shorten my rearlines straight away on new kites/bars, as I am one who prefer the kites to ride "tight" when I want to, and I need to be able to feel the stall point to utilize the kites to their max
You might also find that you DONT want shorter rearlines, as you might choke the kite instead, but lets hear from you how it goes.