Many years ago, my bank bought a smaller bank that did more-or-less what you described. The only problem was that they didn't or couldn't service the loans according the the one-of-a-kind VR notes. Years passed, we entered the picture, and TOOK A BATH cleaning up the mess. Every loan note had to be analyzed (by attorneys and experienced lenders), all payments were ripped off, and then (using the rates and methods actually stated in the notes) all payments were reapplied. Overpayments (there were many) were refunded...not at the note rate, but rather at our state's (higher) legal rate. The moral of this tale of woe is that you set yourself up for mismanagement of a portfolio when you allow deviations from your established products.
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...gone fishing.