@anandtechreader
Do you realise that Windows and Linux can share file systems?
For example, I migrated from Windows to Linux as my primary OS (from just Win7 to Lubuntu + Win10). The bulk of my storage capacity is a 1TB HDD formatted NTFS to Windows can see it natively and Linux hasn't had any issues talking to it right out of the box without any configuration work required.
There is also an ext4 driver for Windows if you wanted to read the Linux file systems in Windows, I don't know how good it is and whether it has write support.
I'm using hardly any space for my Lubuntu install. I've got it on a 128GB SSD, and 90% of the capacity used is my home folder, and 99% of that is used by a Windows 7 VM image. I've got a small amount of "current" personal data on that drive and the rest is on the HDD. I just think that if you're thinking of dual-booting and you're allocating that much capacity for each OS and related data, you're bound to end up with duplication because there'll always be some stuff that you want to access in both operating systems.
I'd certainly advise having operating systems installed in separate partitions though.