You (and your friends) might want to consider the use of removable HDD/SSD devices as a viable option.
The beauty of installing removable HDD/SSDs in a desktop PC is that the user can easily work with multiple drives each drive effectively isolated from each other (when desired) containing different operating systems (if desired) and accommodating different storage needs.
Through a simple turn of a mobile rack's keylock or pressing its power switch the user can thus boot to this drive or that drive without the need for any "bootloader" or any other multi-booting software, as well as avoiding the need (in most cases) to access the motherboard's BIOS to change the boot priority order in order to boot to this or that particular HDD.
With removable HDD/SSDs the desktop PC users have an UNLIMITED number of drives to work with should they choose without the need for opening their computer cases to install the drive in the machine. Again, each removable drive is isolated from the other drives at the user's option.
We've been working with removable hard drives for about 15 years now and have installed or helped users install hundreds of these devices over those years. By & large we've found this desktop PC hardware configuration a most desirable one for the great majority of desktop PC users. And we've found that the only regret virtually every desktop PC user of these devices has had is that they didn't install them sooner!
These mobile racks come in basically two types of configurations - some are two-piece affairs - the mobile rack itself and the inner tray or caddy (in which the hard drive (HDD or SSD resides) that slides into the rack. They come in all-aluminum models or a combination of aluminum-plastic, or all-plastic, ranging in price from about $15 to $50. A Google search for "removable hard drive mobile racks" will result in a wealth of information on these products and their vendors.
Currently we're working with this device...
http://www.newegg.com/Product/Product.aspx?Item=N82E16817995104&cm_re=athena_power_mobile_racks-_-17-995-104-_-Product
It's an "updated" version of the device we've been using for many years. While it's an all-plastic model it has proven very reliable for us. What we particularly like about it (aside from its reliability and reasonable cost) is that rather than use a keylock mechanism found in most devices of this kind, where one needs a key to turn the power on or off, the device has a simple push button to do so. The removable tray which contains the drive is equipped with a simple push-to-release lever that easily physically connects or disconnects the tray from the rack should the user desire to do so. So changing from one storage drive to another "on the fly" is a piece of cake while the system is running. As you will note from the Newegg offering additional removable trays are available (although given the cost it's probably more sensible to purchase the unit (rack + tray) as a whole).
There is no hassle of any consequence in fitting one or more removable racks to one's desktop PC. The installation of these devices is simplicity itself - no more difficult than installing an optical drive. After the rack is installed you just plop the HDD or SSD into the removable tray (caddy), make two simple connections (power & data cable), and slide the tray into the mobile rack. Understand that when you install a removable HDD/SSD device -that's it. You're not installing/removing the rack itself. It's a permanent part of the PC in exactly the same way that one's optical drive is.
(Unfortunately this mobile rack is designed to only house a 3 1/2" hard drive in its removable tray. Four screws are provided to secure the hard drive in the tray (although truth to tell since we frequently switch HDDs we rarely ever use any of these screws and simply slip the HDD in the tray unsecured - connects perfectly to the rack's SATA power/data connectors).
As indicated, the mobile rack is not designed to house a SSD (2 1/2"). Like many users we've been continually switching over to SSDs and pretty much phasing out our 3 1/2" HDDs. We've been able to install our SSDs in the removable trays by using hard foam inserts (the kind of foam usually found in packaging materials) and so far they've worked pretty well. Heavy-duty packaging tape is another option.
We've also drilled two small holes in the base of the removable tray, lining them up with the front screw holes of an SSD so as to secure the SSD to the removable tray. (The placement of these SSD screw holes is standard for both 7mm & 9mm SSDs). But of course it would be so much more desirable for the device to be designed so that it could accommodate both 2 1/2" & 3 1/2" drives. Judging from the current design of the removable tray it would appear that a relatively simple manufacturing modification of the tray would allow the installation of either size drive.
Naturally one's desktop PC must contain at least one vacant 5 1/4" (or 3 1/2") bay to accommodate the removable HDD/SSD device. Multiple vacant 5 1/4" bays in the PC case can be an advantage since mobile racks can be installed in each of the bays should the user desire this configuration.