To really know the difference - one should test it

I wont do that. I`ĺl show you how to adapt it so you can test it yourself. I can`t try every rom that looks promising.
So it goes like this:
Apps used:
Notepad++ (portable)
7zip
Open Baidu rom zip file in 7zip.
Delete Recovery folder.
Go to:
META-INF/com/google/android.
Drag updater-script file from 7zip window to desktop (or somewhere else).
Leave 7zip window open.
Open Notepad++ and run it, open your dragged updater-script file.
Change phone version - replace u8818 to u8815 to look like this:
assert(getprop("ro.product.device") == "U8815" ||
getprop("ro.product.device") == "u8815" ||
getprop("ro.product.device") == "hwu8815" ||
getprop("ro.build.product") == "U8815" ||
getprop("ro.build.product") == "u8815" ||
getprop("ro.build.product") == "hwu8815");
(just
change last numbers
8 to number
5)
Delete only the next lines (leaving empty space after deletion):
format("ext4", "EMMC", "/dev/block/mmcblk0p12", "0");
package_extract_dir("recovery", "/system");
set_perm(0, 0, 0544, "/system/etc/install-recovery.sh");
Save your updater script file and drag it back to your (still open) 7zip window
in
META-INF/com/google/android folder (it will automaticly replace old version)
Still in 7zip window:
Remove chinese apks from
system\app like this:
Remove *.apk and its *.odex part
BaiduBrowser.apk
BaiduClickSearch.apk
BaiduImageSearch.apk
BaiduInput.apk
BaiduMap.apk
BaiduMarket.apk
BaiduMusicPlayer.apk
BaiduNetworkLocation.apk
BaiduReader.apk
BaiduUserFeedback.apk
BaiduWangpan.apk
BaiduWeather.apk
FindmeDM.apk
NewPhoneWizard.apk
P2P.apk
P2PScenes.apk
SearchBox.apk
VoiceAssistant.apk
Just close 7zip window and thats it.
For Shendu rom, you dont have to change version number and you remove some other apks.