Though already sa long time ago:
Just to add on Phil/Mike/Bill's comments: This kind of data will be difficult to fit with FDE standard knots. you either want to try fourier (though this could overswing on one side) or P-Splines where you adjust the knots closer around the peak variations. This will help to eliminate the effect of smoothing. Often this is not important but if you are interested in the different positions of the peaks (hight, auc, ...) this might become important.
From my past work in with seismographic and signal processing customers filtering the noise was important, there FDE still lacks of good filtering techniques. This would help in the data processing a lot I believe.
However, I would give it a try and see how good you can be (currently). Though I like nonlinear and curfe fit platform I'm not that convinced they will do a decent good job either
