Spike,
I was getting similar (prounced cross-hatching) results with my TS 55 and 48 tooth blade until I reset the toe. When I contacted Festool, they admitted that some saws were erroneously set with toe-out rather than toe-in due to some errors in training their employees. I rate this the most likely cause.
I have also experienced some blade wobble due to debris on the mounting flange or not getting the blade fully seated when mounting it. On my saw and blade, the radial clearance between the arbor and the hole in the blade is very small, and it is possible to cinch the bolt even though the blade is not fully seated.
Even after proper adjustment and with a fresh blade, I do not get as good cut quality as shown in David's photos of ripped poplar, but they are very close.
Another cause, I think, that occurs when I make long rips, e.g. trimming an oak passage door, is that the pivot pin mechanism that joins the base of my TS 55 to the motor/arbor has a slight degree of slop. Even with the base adjusted so their is no play relative to the guide rails, the motor/arbor can move slightly in or out relative to the rubber strip on the guide rail. Thus, consistent operator technique in pushing the saw along the guide rail influences the quality of the cut. If I have to change hand, arm, or body position while making a long cut, I am likely to get some cross-hatching or a slight step in the cut edge where I made the transition. But even this irregularity is slight and not hard to sand or scrape away.
I have spoken with Festool USA about my TS 55 and they consider it normal. I think they should modify the procedure they use to fit the pivot mechanism to obtain tighter tolerances.
Dave R.