If somebody had taken out large bank loan or mortgage prior to the hyperinflation of say 200,000 marks, could they have paid off that once expensive loan with the same worthless currency which at that point would otherwise only buy them a loaf of bread?
Yes. Many large industrial concerns borrowed large sums for investment, and paid them back in depreciated bills.
Not all German traders and industrialists had yet given up hope for the mark, but few were not doing their best to protect their businesses in advance — a protection which could only be bought at the expense of the State and thus made their fears self-fulfilling. Where possible, they tried to create credit balances abroad, usually by direct arrangement with their customers or commercial friends: they would under-invoice their exported products sold (for example) in The Hague and buy in return imports for which they were over-invoiced. Such manoeuvres had the extra advantage of avoiding taxation in Germany. Carried on on a large scale, this kind of thing would have tended towards the mark's inflation. If continued, the eventual outcome would be insolvency for Germany as a country although its subjects might hold considerable assets outside. The process was particularly reprehensible not simply because the exporter's profit was the country's loss, but because part of that loss was in the substantial subsidies — of workers' food and of industry's rail costs — which ensured the competitive prices of Germany's manufactured exports. In practice the business of under- and over-invoicing was probably not wide-spread, simply because all a German exporter had to do, provided he had no need to bring his profits home, was to pay his foreign balances into a foreign bank where the tax authorities could not get at them. In any case, so long as plenty of foreign currency was received and enough of it returned, the net effect on the mark was likely to be beneficial. "When Money Dies," p. 36.
A good further source is the book 'When Money Dies' by Adam Fergusson, which gives details about some of the companies/regions that benefited. For an Austrian perspective on the same issue, look at 'Blockade' by Anna Eisenmenger. (quoted in Fergusson's book.) Her story details the immediate reality of the Austro-Hungarian collapse in 1918/9, and its effect in Vienna. A large part of both Germany and Austria's population essentially lived rent-free due to laws fixing rents in place. Farmers, who had tangible daily necessities, were able to trade food for pianos, furniture, and other luxury goods during the height of the hyperinflation. The vast majority of people did not benefit, but would at least be able to 'keep afloat' if they were working. You may have seen how people would be paid multiple times a day, and rush out to spend the paper on something, anything, tangible. Demands for higher compensation by labor also fed into the hyperinflation cycle - workers could and did demand higher wages to continue work. At the opposite end of the spectrum were those on fixed incomes - retirees, pensioners, landlords.
On December 15 1919, Frau Eisenmenger recorded that, whereas the downward movement of the krone in Zurich had gone on, 'the value of my industrial investments is rising to an extent which seems to be incomprehensible and almost makes me uneasy ..." Her daughter was able to make two dollars a day at the American Mission, which could be exchanged for 400 krone, only 100 krone less than the monthly pension of a retired privy councillor. Former civil servants and officers are undoubtedly the poorest of the poor in Austria today. They are too proud to press their claims, can get no employment. Thus it happens every day, again and again, that elderly, retired officials of high rank collapse on the streets of Vienna from hunger. Frau Eisenmenger let a room to the gentleman from the American Mission — just as Garbo's father in The Joyless Street was able to do — and received for it ten times the rent which, in accordance still with the wartime rent restriction Act, she herself paid for the whole flat. On a now slender quantity of negotiable cigars, on her daughter's earnings, on that rent, and on the diminishing real income from her burgeoning shares, she tackled the first months of 1920. Speculation on the stock exchange has spread to all ranks of the population and shares rise like air balloons to limitless heights ... My banker congratulates me on every new rise, but he does not dispel the secret uneasiness which my growing wealth arouses in me ... it already amounts to millions.