I agree with your conclusion, but as interests are paid daily the correct formula for balance after x years would be
f = (1+RATEPERDAY/100)^(365*YEARS*EFFICIENCY)*INITALBALANCE=
with EFFICIENCY = the percentage of time you expect your offers to be taken as opposed to waiting to be taken.
So the difference is even more pronounced.
Notice the way the funcion blows up for higher rates, gotta love exponentials

That is the formula I used basically, except without the efficiency calculations since that is my actual average return rate after fees, and counting for efficiency, not just what I lend out at. If you want more details on how I got this number, check here: