This discussion seems to assume doping is an either/or proposition. In fact, evidence suggests that anti-doping efforts in the past few years, while certainly not eradicating the practice, have forced riders to do it more carefully. It's well known that after the EPO test was developed, riders continued to use the drug, but generally by carefully timed microdosing. This presumably does not result in as much performance enhancement as using all you want, whenever you want. I have also heard on the grapevine that blood transfusions are made in smaller volumes now, to reduce passport fluctuations.
Riders may not be too concerned about having to reduce their doping, since they figure everyone is in the same boat. If, hypothetically, Tuft finished 5th among a certain group of TTers, all of whom were doping at a maximal level, his finish might not be expected to change much if all these competitors were forced to reduce their doping to the same, lower level. But--beyond the old debate about high and low responders--you could argue that the presence of doping controls is more likely to shake up the rankings, because some riders may be more knowledgeable than others about the new limits--or more willing to test them.
The bottom line, as I see it, is that every time there is an advance in anti-doping testing, it spurs innovative ways to beat the tests. Even experienced dopers may not have equal access to these innovations. Some are more likely to get busted than others, while others may, out of fear of getting caught, reduce their doping to levels below what their more knowledgeable rivals are getting away with. Even undoped athletes see variations in their performance from event. The flux occurring in doping protocols insures another source of variation.