They really become much less grippy but its that slow your riding style will adjust to match it, I replaced some original High Rollers that have been on at least two other bikes, the rear was well worn to the point where all the centre section was well rounded, it certainly dragged a lot less but braking efforts were increased due to the due ramped edges rounding off, also climbing but not that noticeable in the dry weather we have had for the past 6 months !
I put HR 2’s on and when braked rear I damn near slammed against the bars, they bit dug in and stopped fairly sharpish
2,000 miles on a MTB tyre is a hell of an achievement
Arkwright would be impressed with that !!!
Well done !