Jim, I was wondering if you could perhaps expand on this a little more. I don't know how many TB of data I have on the WHS, but it's a lot (not as much as you had though). It backs up the other PCs in the house and stores all of our music, photos, home videos and dvds as well. I would imagine occasionally editing the photos or videos. In doing so I would think it'd be best to copy the file(s) to the iMac, edit them, then save the edited version back on the WHS. That way they are backed up regularly and the laptops have access to everything. I would imagine that iPhoto or iMovie could see the whole library on the WHS (like I can do now with Picassa or Windows Live Photo). Are you saying this wouldn't be a good scenario?
I bought my WHS boxes back when we were all using PCs. At the time our family of 4 had two desktops and 4 laptops. All 6 machines were being backed up nightly to the WHS. We also kept our "family collection" of music, pictures and videos on the WHS.
Now, we have all have iPhones, iPads, MacBook Airs, and iMacs. We have a single PC left in the house (a 5 year old W7 machine with a gorgeous 30" 2560X1600 monitor). Nobody even bothers using it anymore. It still is backed up to the WHS, but it is a moot point because the data has all been migrated over to Macs.
The concept of "moving files to the Mac" to edit... then moving back to the WHS seems barbaric to me. Let's take a look a photos as an example. Back when we were using PCs, we would keep our pictures organized in windows folders by "year"... and then further categorized by "event". So for example we might have a 2011 folder containing the following sub-folders:
2011-01-01 New Years day
2011-02-15 Ski Trip
2011-03-17 St Patricks Day Parade
...
2011-12-25 Chritmas
2011-12-31 New Years Eve
Now, with the Mac, my 10's or 100's of thousands of pictures live inside of Aperture 3. They are still organized... but they are also 1* - 5* rated, event tagged, people tagged, GPS location geotagged, etc. Let's say someone comes over our house and we want to show some slides. Within lieterally seconds, I can create an A3 "smart album" that (for example) contains pictures rated 3 stars or greater, containing pictures of our friends, filtered by the location being our beach condo only during the years from 2000 through 2011. Seconds later, the new slideshow will be playing on the iMac screen... or shipped to any of the TVs in the house through that Apple TV. This would be impossible to do in the past when our pictures were globbed together in funky windows folders.
Now A3 does allow the pictures to live "outside" of A3... using a technique called "referenced masters". The interface to the WHS is clunky enough that I would not trust using the WHS as the repository for any referenced masters. Instead, at a minimum I would be looking for some better direct attached storage solution such as Firewire or Thunderbolt drives. Still, it is easiest if the entire library lives on the main hard drive of the iMac... as long as your HDD is large enough to contain it all.
Currently, with fairly extensive library... everything fits comfortably inside of my 2TB iMac. I have about 1.2 TB of data between my music, photos, camcorder videos, documents, and ripped DVD movies. Of those... my ripped DVDs are my lowest priority thing on my iMac. In fact, when I rip a DVD... I keep the "full MGEG-2" copy on my WHS, and I keep the smaller MGEG-4 (H.264) within my iTunes library. I really do not care about the original ripped versions that I keep on my WHS. I could easily re-rip them again if needed... and to be honest, I am not too sure why I even want to keep a video library collection anymore. As the world moves to "any movie in the world" available for streaming... why do I even want a video collection, rather than just stream on demand?
Now, most of my 1.2 TB data collection is VERY important to me because they contain all content that cannot be re-created (except the MPEG-4 movies and music). Our photo collection, 25 years of camcorder videos, and our documents can never be replaced. The entire data collection is backed up every hour to a Time Capsule in my house. This gives me the option of completely rebuilding any of our Macs (iMacs or MBA's) within minutes (MBAs) to overnight (iMacs). More importantly... all 1.2 TB of data is backed up the the cloud using a secure cloud backup vendor. I am currently using Crashplan+... which is an incredible deal at unlimited backup for just $3/month (single machine) or $6/month (unlimited family computers). I am on the family plan, and all of our computers... including my college students living away from home (even outside of the country), are all backed up to the cloud every 15 minutes. Even the old PC that mentioned earlier is backed up. The only thing that is not backed up is the WHS... so if my house burns down, then poof. As I said... I really do not care about the WHS anymore... so it would not be a big loss.
The situation is ideal. All of our data lives on iMac which is on 24/7. All of our MBAs synchronize to the iMacs so we have all the data we would possibly want with us during travel local on the MBAs, and cloud synchronized back to the iMacs. All of our data is backed up twice... once locally inside the house (for ease of recovery), and secondly to the cloud (for disaster recovery).
At this point... I am scratching my head wondering what I need to WHS for anymore. It had value when it was backing up 6 PCs... but those days are behind me as I have moved to Macs and Time Capsules.
Hope this helps.
/Jim