Convert filesystem from EXT4 to RFS

[5vb]

I've installed Cyanogenmod 11 and want to revert back to the stock firmware. However, I didn't create a nandroid backup beforehand so if I restore the stock ROM, I always have to factory reset so there's no way to have my stock firmware with all my data. Cyanogen converts the filesystem to EXT4 so I always end up in a boot loop after restoring stock ROM unless I wipe data/factory reset.

I want to know if there is a way of converting the filesystem to RFS from EXT4, I have CWM and am rooted.

I have a Samsung GT-I9500 and I'm using Odin v3.07

 

[gxgs]

Titanium backup? then format data, then restore.
What kind of data you refer to? apps and their data or also the internal user storage?

If you are going from CM to touchwiz a factory reset is kind of mandatory considering you are going from AOSP to non AOSP. The way CM handles and sets up databases and the other files in the data partition is different. Even if you manage to use the same partition, you will end up with force closings, or bootlops.
The only scenario where developers recommend a dirty flash is when doing minor software updates of the same ROM.