Onus :
The 7200RPM drive will be faster on sequential throughput than a 5900RPM "Green" (or LP) drive. My biggest concern would be reliability. The frequent head parking of Green drives has been problematic for some, prompting firmware fixes to reduce it. I'd probably keep any drive to 2TB.
Actually, sequential transfers can easily be greater on a greater capacity green drive, such as a 2TB 7200RPM drive versus 6TB green. 2TB 7200RPM is at about 140MB/s on the outer edge, maybe a bit more. 6TB green is about 200MB/s.
Random transfers are different where higher RPM, seek time; (access time) helps more.
I got a Seagate ST6000DX000 6TB 7200RPM drive a while ago. It does automatic head parking, very aggressively! There is no firmware update either to fix it and it causes a delay because it takes about a second for it to come online again after parking the heads. Have to use Crystal Disk Info to have it automatically disable power saving and acoustics every time I turn on the drive.
https://www.youtube.com/watch?v=2wau6aMYR08
But most 7200RPM drives don't park there heads. That should be an option to disable on the green drives, especially since they make a clunk whenever it happens, including some laptop drive, don't want to engineer it to be quiet.