We have done a whole bunch of customizations to ERPNext V4 by adding custom fields and modifying existing doctypes through custom scripts calculations,and also by creating a bunch of new modules and new doctypes.
We have been skeptical about migrating and upgrading to V5 , coz we fear we may lose most of the customizations, owing to the new look and significant changes done to the different doctypes in V5.
So, can customizations be imported while migration and upgradation to V5?
If no, how shall we go about the upgrade, so as not to lose the customizations?
Thanks in advance 
Regards
Rajat
VizExperts India Pvt. Ltd.