T420, should I finally make the win10 dive?

I use a T420 (upgraded core I7 quad core, 12gB ram, 256gB solid state)
I currently dual boot win7 pro and kali linux. I've stuck with win7 cause it's what I know, and never had a reason to upgrade.

Is it worth the upgrade if the upgrade is free, even if I have no particular "reason" to run 10?

If I had the storage space to give up, I'd run triple boot, but my 256gB is my only storage space. I need to replace my 1tB ultra bay that took a crap...

Also how much space does win10 take...

T420, should I finally make the win10 dive?

T420, should I finally make the win10 dive?