Mostly I was planning on rehashing some old hardware and was planning on doing a slow but gradual build up of storage space mostly using onboard raid or a software alternative thru simple mirroring.
WHS was attractive because
A) I didnt know the alternatives at the time and low system requirements
B) was supposed to help ease my backup routine so I could have a more up-to-date back up of my main system and I heard WHS made it very easy to setup an automatic backup.
C) Its Windows! so its familiar
So I bought this roughly a few months ago and eagerly anticipated a HDD deal so I could scoop up some drives to set up in RAID1 and add it to one of my previously mothballed S775 setup.
Well a few things happened during when I got the software to now.
A) I became super busy at work so I didnt have time to deal with any of this so left this project hanging. Giving me time to research and lurk on [H]'s Storage and SFF subforums.
B) Realized that HDD prices will probably stay relatively high for bit longer, so mirroring becomes less attractive since its very inefficient use of space
C) B led me to considering RAID5, which led me to find out some of the weakness of onboad RAID5
D) Because of (A) I had a newfound desire to do a mini-ITX build so that it could blend in well with my small living space (condo) instead of having a giant tower sitting in my living room. So decided to scrap my old setup and start fresh
E) Discovering that FreeNAS is free and can be installed on a USB drive freeing up all six SATA ports for HDDs and the ability to do double parity (RAIDZ2) if I so choose for more protection.
F) My data has grown exponentially over the last couple months since I have been busy ripping Blu-Rays so I needed a larger capacity which coupled with (B) argued for (C) which led to (E)
Basically I realized that though WHS would probably be adequate for most of my uses, I wanted to flexibility and the savings to certain degree of setting up a large pool of drives once that was decided and form factor of the new build decided I wanted to try something new OS wise, this I totally blame on [H] as well as the urge to scrap old parts and build a cool miniserver got that idea from here as well. Which led me to FreeNAS and ZFS, thought Ubuntu and couple other Linux based solutions wouldnt be out of the question.
Lol didnt intend to make a quasi logic tree but hopefully explains how I changed my mind over time.
As far as benefits over Win7, I cant really answer your question since I have never used Win7 for this purpose or WHS2011 for that matter. All I know is that WHS2011 is much cheaper than a full OEM copy of Win7