This was true 10 years or so ago but with todays string material and technology string stretch and creep has all but been eliminated.

I have found it is just as easy today to keep a dual cam bow in time as it is for a single cam.
Plus with a dual cam bow you can creep tune them or as Pinwheel12 calls it super tune them which is something you really cant do with a solo cam.

On another note with the BT dual cams their draw force curve is stout as in they pick up the weight quick and keep the weight throughout the draw cycle.
If you are currently pulling 70lbs then look at the Pat Dually in a 60lb' s you will have less weight to pull but will have more speed and power.
My current Pat Dually at 60lbs is faster than my 02 single cam Pat set at 70lbs using the same arrow.