hi truckmount, here are some thoughts for you,
you might already be aware, that the drobos also feature some kind of drive redundancy, (single SDR or dual DDR), in that essentially any 1 drive (or 2 drives for ddr) could fail, with the data still being there on the remaining ones.
if you also wanted to back up the drobo data somewhere else, you could use some backup tools, (such as syncback for windows), or could just get a bunch of stand-alone drives and use them via a usb caddy to copy and paste your data to.
Alternatively, you could get another drobo with similar configuration, and backup your data files to it. this way, you would have a similar data backup if your 1st drobo and drives fail, (upto the last backup) and would also have a 2nd compatible hardware chassis, in case the 1st drobo chassis gets hit by a power surge or something, and could then follow the migration process to essentially use your 1st drobos diskpack, into the 2nd drobo until you can replace the 1st drobo - for example as mentioned here:
I actually had a older gen1 drobo, with selected data files & folders being backed up onto a gen2 drobo, using syncbackSE software on windows, but i also have extra backups of specific data onto a standalone usb caddy hard drive.
if the main user is going to be 1 user at a time, rather than multiple users at a time, then a Das unit seems very good.
(you could always have the das drobo hooked up to 1 computer, and have that computer act as a server for the other people in your shop to use, especially if it is just to copy some files from the drobo to their computer, or just to copy different files to the drobo for storage of their stuff - but please bear in mind that if you were using the drobo at the time, there might be a bit of slow down for the duration of their transfers etc, or if they want to copy something you have open, there is always a possibility of a file being locked, but that is also the case with other devices or programs etc, especially excel files over the network)
i have used several das drobos for audio or video editing, without issue myself. i think it included 25000kbps
width=1440 and height=1080 (and a mixture of files with an older gen1, gen2, drobo-s-gen2, or with my newest drobo which is 5d… havent tried a 5dt yet but here is a thread with some more info for you:
the 5dt seems to mention performance boosts, so might be quicker for you then another das.
im not sure what exact drives you would be getting, but you might as well enquire before buying, possibly with the sales team, just to be 100% sure.
there was also a question regarding drive speeds here with some info. (the post was about a nas though i know you mentioned das): http://www.drobospace.com/forums/showthread.php?tid=146526
whenever i do editing, i usually keep the source files on a drobo, and simply output the finished render onto my local computer to be a bit quicker, (where i can then burn a disc from, or check if happy with the result, and can then copy that back to somewhere on the drobo) but i have outputted files to a drobo as well, or burned from a drobo before too.
hope this helps a bit.