I have a masterpiece 2400 and the Humax 7500, the masterpeice is fine with padding only the humax has issues..
I seem to be missing both lead-in and lead-out padding, so my shows are exactly 30mins or 60mins etc
The shows I have noticed it on (off the top of my head) are 'Alcatraz' and 'Bondi Rescue' which are on Nine and Ten... [edit] I have just checked and ABC does it too, maybe 90% of the time, though I noticed that 'Top Gear' seems to be OK...
I tend to agree with an earlier post, in my experience the topfield seems the most reliable, the strong units reset all the time and get patched constantly without fixing anything until they discontinue the unit and stop supporting it, and I had nothing but trouble with the Beyonwiz DP-2 (exchanged for my topfield masterpiece) though others seem to love them..