There's a Chenbro (I think) that's been in a boot in the back corner at VMworld about the last two years very similar. Drives are hot swap by way of lift out and 45 degree slide into the bay. Limited on expansion off the back and didn't have on board RAID just multiport SATA. So good for ZFS, Storage Spaces, possibly even VSAN. If I recall they had another that had two trays of 16x 2.5" bays as well. Drive maintenance on that was pretty much 'maintenance the node, work on the drives, return the node to cluster'. But super dense and a lot interesting.
Similar was a 1u box where the 2.5" drives were not front removable, mounted at an overlapping 45 degree angle but got like 16-20 across the width. Oddball stuff, but equally interesting BECAUSE it was odd.