Nathan -

The advantage of spiral fluorescents is energy savings. The disadvantages are the linger glow problem mentioned by others, and the fact that there is a pronounced warmup characteristic that results in lowered light output for the first minute or so after they are turned on.

In a darkroom, the lights are off most of the time. When you turn do turn on lights, you expect to be able to immediately do whatever you need light to be able to do. Having spiral fluorescents would not be helpful. Yes, you might have to pay a bit more in energy cost for the few minutes that incandescents are on, but because that is likely to be a very small period of time anyway, I think the cost is justifiable in terms of the convenience.

Energy savings is a noble thing to do, but there are times when common sense must prevail. Use incandescents.