Transverse flow effect or "inflow roll" occurs due to the unequal distibution of induced drag across the disk. The front half sees less induced flow, the rear sees more. This unequal drag/ unequal lift causes a roll toward the advancing side (right in a Bell). Its most noticable as you transition from the hover(high induced flow across the entire disk) to forward flight. Once the initial transition is made and the roll is countered by that lateral cyclic, you will not see much of a need to continue to correct for it. As for dissymmetry of lift(if you want to call it that) it causes the aircraft to pitch up, due to blowback, and would tend to "slow" the helicopter if the pilot did nothing. The way we counter blowback is by applying more and more forward cyclic as the airspeed(and dissymmetry of lift) increase. all of this assumes a perfect world, textbook model, and does not account for other forces at work. so your result may be complicated by other interferences. but in the end, ETL is when the disk has a greatly reduced induced flow due to forward movement in the airmass. Transverse flow shudder occurs just before you get to ETL and is basically when "half" the disk is through ETL.