I use a USB-OTG flash drive, they work really well with the One
TWRP lets you choose where you want to backup / restore
just click where it says internal storage xxxmb and choose the usb-otg ...it's easy to do what you want when the files are safe on the flash drive
Here's the ones I use >> http://www.amazon.com/Kingston-16GB-...3&keywords=OTG
If that's the case, then I am better off flashing TWRP within seconds, rebooting to bootloader, taking the nandroid back up on TWRP, transferring the backup to the laptop, google drive and keeping one on the internal storage then flashing reflashing the stock recovery.
Would this process be simpler and cost effective?
I was able to install multiple OTAs with my unlocked bootloader (S-OFF version, not HTCDev), I can easily reflash stock recovery, nandroid backup will restore 100% stock rom and kernel. The only factor I see that could affect OTAs would be root. Do you think I am now future-proof in terms of OTA updates? That is the only reason why I went through this arduous process, it was to ensure that I can modify my system how I please but when an update arrives, I could just restore stock rom and kernel from nandroid, reflash stock recovery and update then modify away.