seems kind of limited
They only support SMB (CIFS) ? Really? I think most would argue that NFS is a far more commonly deployed protocol amongst servers anyway.
I suspect these guys are not using RAID as in mirroring whole drives, they are probably mirroring (or more likely triple mirroring) objects across systems. So if a drive fails the objects are mirrored elsewhere, you don't need to wait on that drive or a hot spare or something to kick in. They may be using RAID for the operating system disk(s) on their controllers (or perhaps just a small SSD).
3PAR has a nice RAID system too which is similar, breaking the drives up into 1GB (as of a few years ago before that 256MB) so rebuilds are very fast and the design is quite scalable. You can even yank a drive out of an array and the system will go into "logging" mode writing data that would go to that drive to other locations for up to something like 7 minutes at which point the system assumes the drive is dead and rebuilds. You can gracefully evacuate drives as well for seamless maintenance.
IBM's XIV does something similar too I believe but last I checked they still limited themselves to 7.2k RPM disks and RAID 1 only (I suspect their CPUs can't keep up with the calculations for RAID 5/6 at that level, with 3PAR that is handled by their ASIC).
XIO (assuming that's what they are called now) does RAID across drive platters, which I thought was quite creative too, they can fail individual platters in drives and not have to replace the disk (system ships with enough spare capacity that you don't take a capacity hit over the 5-8 years or so of the system warranty).
It's not uncommon for a 3PAR array to have more than 50,000 RAID arrays on it with just a few hundred spindles(much more for those on systems older than current generation since the size of the chunklets is smaller).