My levers and brakes were replced buty are we just talking about 2009 machines. Mine was a 2008 bike.
Mine is a 2008 bike and I have received and fitted the new brake caliper, the difference is astounding!
My take on the brake issue is this:
The original 2008 bikes were fitted with levers and calipers that used short cable travel like centre pull brakes do, this was an obvious problem on the rear V brake and made that better immediately the levers were swapped. Replacing the cable with a high quality lubricated system helped somewhat but not enough.
Not so obvious at the time was that the Promax caliper also used less cable travel and the leverage required was lost with the change of levers, this wasn't immediately apparent as the Promax didn't work well with the original levers. Now that I have the APSE levers and the new calipers fitted the previous poor performance is obvious.
I believe (guessing) the new brake comes with organic pads, these are optimal for a town rider offering excellent braking in short spurts but can overheat on long downhill sections. Unfortunately there is no ideal brake pad and people who have very long descents may wish to opt for sintered or semi-sintered pads, the trade off is slightly reduced braking performance and greater disk wear but with reduce pad wear and less prone to overheating. You could use the rear brake for speed control during the descent and then the front brake to stop quickly.
Sintered pads apparently suffer less in the rain than organic pads but I haven't been out in the rain to test this and I doubt they would be anywhere near as bad as the original Promax brakes.
I might be wrong about the Promax using less cable travel but it seemed apparent to me even before I had fitted it to the bike.