Terms and rationale:
Volatility is high, liquidity is low. Being able to repeat the cycle quickly is the first priority.
Unlike most loans these don't run forever. As there is a likelihood of loss for both lender and borrower, it seems some mutual concessions are in order.
Interest, especially compound interest, is ludicrous right now. Loan fees are used instead. All loans shall end and not be renewed. The service may be reused.

There are three periods:
Repayment period: During this time the full loan amount will be repaid with only fees remaining on the balance sheet.
Fees period: After the full amount is repaid, the fees are paid over a longer period of time.
Settlement period: Any outstanding fees or principal not paid shall be cancelled after this time.

Concessions:
The settlement period is one. Larger loans have lower fees compared to principal.

Loaned    Repayment   Days     Total fee    % fee  Days   Collateral
Personal loans   Settlement 15 days
1BTC       0.2000BTC   5 days    0.2500BTC  25.00   2 ds    0.2250BTC
3BTC       0.5000BTC   6 days    0.6900BTC  23.00   3 ds    0.5950BTC
6BTC       0.7500BTC   8 days    1.2600BTC  21.00   6 ds    1.0050BTC
Miner loans      Settlement 30 days
10BTC      1.0000BTC  10 days    1.9000BTC  19.00   4 ds    1.4500BTC
30BTC      2.5000BTC  12 days    5.2500BTC  17.50   6 ds    3.8750BTC
60BTC      3.7500BTC  16 days    9.6000BTC  16.00  12 ds    6.6750BTC
Trader loans     Settlement 45 days
100BTC     5.0000BTC  20 days   14.5000BTC  14.50   8 ds   10.7500BTC
300BTC    12.5000BTC  24 days   40.5000BTC  13.50  12 ds   26.5000BTC
600BTC    18.7500BTC  32 days   75.0000BTC  12.50  24 ds   46.8750BTC
Business loans   Settlement 60 days
1000BTC   25.0000BTC  40 days  115.0000BTC  11.50  16 ds   70.0000BTC
3000BTC   62.5000BTC  48 days  330.0000BTC  11.00  24 ds  196.2500BTC
6000BTC   93.7500BTC  64 days  630.0000BTC  10.50  48 ds  361.8750BTC
Settlement
Fee:       0.1000BTC per remaining BTC
Minimum:   0.0100BTC per principal BTC per day