That is precisely what I did for my 2x IBM M1015s, that I have flashed to the LSI 9211-8i firmware. Yep.
And I can confirm it worked on the IBM 1015s, flashed to that 9211.
It was kind of a PITA as I had to disable driver signature for the entire OS via PowerShell command line to get the drivers installed. Those instructions you posted won't work as-is, you have to disable Driver Signature on at least 2012 or higher.
X58 platform, i7-950, 2x IBM M1015s, 12 HDDs (3 SSDs, misc fans)
System @ idle before INF change: 230W
System @ idle after INF change: 135W
Each 4TB Seagate NAS drive I have measured at 8W at idle when not spun down. And this confirms it (12 * 8W = 96W), which is the exact difference you see above. Everything measured at the wall with a Kill-a-Watt.
But... The "Version 14" windows drivers I installed (Windows Server 2012, non R2), disabled SMART access to my drives. That, I did NOT like. I use StableBit DrivePool and Scanner (SMART monitor) <- and this is the ONLY reason why I am still on Windows. I run Linux for everything else.
FYI, new system with HDDs spun down (under Linux) idles at 75W (E5-2690V3 ES, X10SRA, 64GB DDR4, 740W Platinum, SC846EL1 chassis w/fans under PWM controll).
I have measured the Backplane taking up 12W and the LSI 9211-8i card taking 9W. I really REALLY thought about using the 10x SATA ports on my X10SRA motherboard to connect to the JBOD backplane (I have a non-SAS2 backplane), as that would drop my overall idle watts down to around 55W !!!
^- Note, everything above was measured at the wall with a Kill-a-Watt. The IPMI chassis watts from the PSU isn't accurate at low wattages.
But, the convenience of having more than 8 drives in my pool, 1x OS drive with no RAID and 1x scratch drive, really limited me.
Perhaps one day when we have 10TB HDDs, I will rebuild the system to less than 10 drives - and lower power consumption back down to 55W.
One day...