I've actually been researching 45 Super and 460 Rowland quite a bit lately out of curiosity. The 460 Rowland really wasn't even a consideration after a short read, and having no SAAMI standards associated with it made all the more uninteresting to me, along with no published load data from folks able to actually measure the pressures they get with those loads--at least none I'm aware of.
But you asked about the 45 Super and I believe it's fair to say that brass is just as available for it as it is for 10mm Auto--you just have to wait until the only source for it that I'm aware of (Starline) is willing to take orders for it, and you place your order. Same as 10mm Auto.
I lost interest in this one, two, since modest ballistic differences in calibers aren't of any importance to me, and not of much interest either. I see almost nothing available that's specifically chambered for 45 Super. SO, given that 10mm Auto ballistics are close enough for my purposes, I know for a fact the round can be loaded very accurately, and a fair number of guns are chambered for it, I just found no reason to introduce another oddity cartridge to the clan.
In the case of 460 Roland, 45 Super and 10mm Auto, small boutique manufacturers may produce ammo with performance claims having varied accuracy, and wildly varying safety, IMO. Pulled-down ammo from some manufacturers that has remarkable performance shows clearly why: loaded to well over maximum specs by all indications.
I'm an absolute 10mm bigot, so I simply have to find something in auto pistol that really impresses me all the away around...and I don't see it. Believe me, I was seriously looking for any excuse at all to get a pistol with more oomph (just for fun), and was this close to getting a DE in 44 Mag. That's when I started the search for 45 Super and 460 Rowland options, and neither makes any sense to me over 10.