I'm not exactly sure how the logic would work, but it's be nice to see a system where we can pay off parts of the loan over time, instead of being stuck with, for example "$2 million/week for 200 weeks or pay off all $400 million right now". Maybe something along the lines of "Pay off X weeks now", where X is the user input, and the cost of paying off in segments is: (Initial Loan (no interest) /Weeks Remaining) * (User Selected Weeks (X) * early repayment percentage factor).
For example, if I have a $100 million dollar loan for 100 weeks at 10%, I will end up paying $110 million, which will cost me $1.1 million a week (1 million a week to pay off the loan + 100k interest), or, I have the option to pay off 50 weeks worth (50 weeks * 1 million base weekly payment = $50 million) plus say a 10% early repayment fee, so I can reduce the loan time by 50 weeks by paying $55 million. Obviously the repayment fee would be slightly higher than the interest but I tried to keep it simple for this example I'm writing on my phone.