Xposed is working good for me. Not as much for the OGP as other devices. I think you will find enough for what you want, though.
Don't know about 10p.
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FreeGee has an option to backup you EFS from within the app. Of course you can back it up in every way you would like. However, you will want to copy the freegee folder (or whatever backups you do) with that backup in it to your external SD or computer so it doesn't get wiped. The reality is, you most likely won't ever need that backup. It's a worse case scenario.
Just be careful when formatting partitions on the OGP. Only format system, cache, and data/media partitions, and doe the regular wipes and you'll be fine.