I have the 2 tuner white Tablo now with a 5Tb HD. I ordered the white 4 tuner and should ship this week.
Do you think I can just take the 5Tb HD from the 2 tuner and put on the 4 tuner and it would work and have all my shows?
Not sure if I have to do a lot of binge watching 
to clear it out or it will save my recordings.
You’ll have to do some binge watching.
It’s not possible to move drives on the 4th gen yet.
OK thanks. I will over the weekend, mine says will ship tomorrow so I have a few days to go through everything.
I have a legacy quad and a 4th gen dual. The quad has a 2tb drive and the 4th gen dual ha a 1tb drive.
The 4th gen will be relegated to recording series and movies that i want to keep and watch every now and then.
The legacy quad will be for short term storage, time shifting and football as long as it lasts.
The 4th gen quad, well, my wife will take it over just as she did the legace quad. I welcome a new quad in the house so I can have some space to record my stuff.
because when you plug it into the new one it will want to format it …hence erasing and losing everything.
You could put a different one on it and watch all the saved shows on a PC
I did not expect it to come so quick, it came today. 
I did not set it up yet and will binge watch 
some shows today on the old white 2 tuner one. Then swap the HD later or tomorrow. Only good thing is not much I really cared about saving when I looked, so can blow thru a lot of shows skipping around.
To hopefully help others, if you connect the HD from the white 2 tuner to the white 4 tuner, it does NOT ask you to format it. While you can’t see your old recordings, the space they used is taken like they are still there.
I had to remove the HD from the Tablo and put it on a computer to do a wipe or format first. Then when I reconnected to the new Tablo, it asked to format it.
Out of curiosity… Before you wiped it, did you try the disk migration steps they have for other systems?
I know it’s not supposed to work for this, but since you knew you had to erase it anyway… JW
It only sees the space that was used for the recordings not the recordings. I would have lost about 1Tb if I did not fix it on the computer. So it can work eventually just they need to tweak it some.
It never technically “asked” me to format the hard drive.
It’s just something you have to do with any hard drive for it to work with the unit.
The “formatting” is basically Tablo loading their files in to the hard drive so their app recognizes it.
My old WDTV PLUS unit used to drop files in to the HD too.
You couldn’t just hook up a HD with movies to it and watch files without that/those files.
Instead of just replacing my 2 tuner with the 4 tuner, I just added it to my account in the Tablo app, bought a second hard drive and connected the antenna to both Tablos. You can easily switch back and forth between the two Tablos. I now have 6 tuner capability and didn’t lose any recordings.