I am really glad that monoprice has such a quality product and a decent price. I would have loved to have found a 5-in-3 on here, but I'm happy with the 4-in-3. All works well thus far. Have 8 of the drives plugged in to a pcie add-on card that provides 8 sata 3 ports.
PROS: Fit in my server chassis without incident. Tray-less hot-swap lockable bays are really nice. Seems to be built well. My system is kind of loud (three 120mm & 2 80mm fans) so I don't notice any audible increase from the contribution of these fans (I have three of them in my system).
The boxes are solidly built.
CONS: One of the lock pins fell out as I was installing one of the bays.
Not able to use angled sata cables.
Potential limit to 3 TB drives.
Lacks detailed documentation.
The locks feel a bit flimsy, I wouldn't trust them to keep someone (little) out.
One of my drive bays has a yellow/red led instead of blue.