Peter, your avatar is toooo funny...and very timely... another use of the word "green" argggg...
So far I have used the Gecko on Baltic Birch, pre finished veneered sheets and melamine. On all 3 of those surfaces, the hold is so strong, one Gecko can lift the sheet... last week cut down 20 sheets of 5x8' 3/4" melamine, gosh they were HEAVY... at times, I used the Gecko to get a better grip on them while pushing and shoving them around. I tested it while the sheet was upright, and the Gecko had a good bite on it... remarkably, I lifted the sheet off the ground, I was stunned.
Some dust is OK, but too much dust will reduce the holding power, but for holding the rail in place, no worries. I imagine the pads will wear over time, and suction will be less. I have cut about 80 sheets so far, still rock solid. But I ordered a few replacement pads just in case. Considering the pads are low cost, these Gecko's will help me out in many ways... even though I only bought the first one to simplify holding the rail (got tired of bending below the material to clamp) Like all tools, there is some tricks.... push down on the locking handle, when securing the vacuum...it makes a big difference.