Ok - time for the after action report
I did the roast in the herbed salt crust - it definitely needs less time and/or heat than a comparable piece of beef. Came out a bit too far on the well done side of things, due to the salt crust, however, it was still moist and nicely infused with the thyme and rosemary aromas. Next time, cooking time will be shortened.
As for the sauce, I made a sauce burguignonne from the veal demi glace sitting in the fridge and some Medoc. Served with pommes macaire and sautéed green beans.
So far, so good. My ostrich skills need work - but then again, the producer is my girlfriend's sister, so I can get plenty of practice material straight from the farm. The pommes macaire where absolutely great, though. Seriously, anyone without a cookbook by Robuchon, get it, if alone for the potato recipes! Oh, and contrary to a lot of macaire recipes floating around in the net, do not cook the potatoes. Bake them in foil for at least an hour, scoop out the flesh, mix with butter and creme fraiche and bake patties of that dough in butter.