Dear veer
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/sikh-sikhi-sikhism/663-birs-copy-guru-granth-ji-scripts.html
what i feel is the gurus baani that a sikh or a human being is reciting singing and trying to embrace in their lives, so it doesnt matter in which ever script it is written, it will always remain guru ki bani and the message too wud remain the same, although its better to have the knowledge of gurmukhi but still i feel that the usage of different scripts will make it more accessible to the sikhs who dont have the knowledge of gurmukhi and not knowing of script should not be a barrier in between the gurus word and a human being
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=663
regards n gurufateh