Adding to the above, sheeit man, just ride one, 99% of us "competitors" ride (and I mean below Intermediate class which can be 4 steps above novice/beginner)... ride bone stock bikes. wear and tear of normal use, over the years, will take some of the edge off any bike. Each year or 2 it seems they change a few things to change how the bike uses horsepower or torque to move you and the bike, 06 was a good year on my 300, I bet it is for 280 as well.
PS, about the pistons and noises... I have a 93 250 gasgas trials bike, has obviously lots of use, BUT... we just this past year, finally honed cylinder (I dont know maybe they didnt even do that) BUT we do know we replaced the piston for oversize/worn bore... SO, point is, trials bikes unless they have had undue stresses (wound up too tight, aboused, and or something went wrong with cooling or just ran with the less oil in premix) last a damn long time, compared to the old air cooled standard automotive cylinder type sleeves. cylinder sleeves are super hard coated, you manage ring wear maybe for most well ridden/maintaned bikes.