In this kind of upgrade very rare cases happen where google removes the unlimited drive from your account. Yes you get a replacement drive because of the Lifetime warranty but your data will be lost. So, I would not recommend you to use it to backup sensitive information over here. and if you do, at least keep a 2nd backup somewhere else.
However, I have a workaround if you really need to backup sensitive data. The idea is to create 2 different unlimited drives then clone the data between them so you have 2 drive with the same data and if google deletes one you have the second to restore your data from. So I will be selling 3 combo regarding this.
Only My method of cloning = $5
2 Shared Drive = $6+$6 = $12 ($2 off) = $10
2 Shared Drive + Method = $6+$6+$5 = $17 ($2 off) = $15
2 Shared Drive + Method + I do the cloning for you = $25
If you want to know what exactly does my Method do, Check FAQ.
Full disclosure, If you want me to do the cloning for you, I will require access to your google account and I will have access to your google drive for the period of cloning. You're free to reset your password afterwards. So don't buy that unless you're comfortable with sharing those details.