For updating an  Android OS which one is better amongst the, official Update and Custom ROM update Possible Duplicate:
  How do I update the OS in my device?
  When will my device get the Android 4.0 update (Ice Cream Sandwich)?  




I am using the Sony Xperia Arc phone.

I came to know that,The Official Mobile Update OHLA(open handset alliances) will be delaying the release of Android OS(ICS 4.0).

I have a little confusion about updating Android OS.I have seen some mobile OS update forums and they mentioned that we can update our Android phone easily to higher version i.e. Android OS(ICS 4.0) by rooting the device.But it seems the mobile warranty will be broken,the data will be lost and even we can find the bugs as well while updating through custom OS though we can update easily. 

So I want clear solution for this confusion so could any one help me for this problem.

What would be my further steps for updating it to 4.0?
According to Sony's official statement, Ice Cream Sandwich (a.k.a. "ICS", a.k.a. Android 4.0) is coming to Xperia Arc at end of April or beginning of March of 2012.  If you are worried about the cons of rooting (i.e. voiding warranty, possibly breaking the handset, etc.) I would suggest that you wait for the official update from Sony and/or your carrier.