Using a Premier XL as an add'l/external HD ?

After finding out in another thread that adding additional TiVo dvrs to a Roamio Pro (host) allows you to see the added dvr at the bottom of "My Shows" and to view the content of it's own "My Shows).

My2TB Roamio Pro has approx 65% of HD space used by programs, TV series and movies I don't want to delete (and plz do not lecture me on streaming, etc. I just want to keep them, ty).

I may have access to a 2TB Premiere XL with Lifetime for $200

Questions:

1. how fast is the trasnfer speed from a Roamio Pro to a Premier XL? say 1 hour HD episode of something
2. can I transfer entire folders at a timer? (i.e. all episodes in the "Nova" folder)
3. will the transferred files & folders keep the same filing structure once transferred to the XL (say by date within the same folder in the XL's My Shows)?
4. is something lost during transfer?
5. will skip mode work when viewing a recording from the XL's My Shows viewing it through the Raomio Pro?

I plan to connect the XL to my 1Gigabit ethernet network using CAT6 but can do MoCa with exsisting coax if t is deemed better.

I may or may not get FIOS cable cards and create One Passes for the added XL, if so ca One Passes be copied over?

Am I missing something or not thinking it through correctly? I feel it can be a cheap, fast and technically easy way to add HD space and create a "zone" just for my stuff, away from the reams of MY Show recordings my wife and teen daughters have/use.

As always, thank you very much for all the input & advice, truly appreciated!

Gman