I just got my replacement SS after the USB socket broke, & yesterday when trying it out noticed one particular sensor not responding even when practically standing on it. Remembering this post, I did a vaguely scientific test today, of standing a heavy block of steel on each pad in turn (I've got four little plastic buttons on each of mine) and noting the raw CC data in MIDI Monitor. I am a bit shocked at the variation, from values in the 50s & 60s for some pads (particularly 1-5), and single figures for others (esp 6-0). The Navpad buttons seem less responsive than the old SS, but I never noticed, or measured, such a variation before. I realise the exact position of the plastic buttons, & the weighty lump of steel will affect the results, but there's a certain consistency in them nevertheless.
This is all raw CC data, nothing running on my macbook other than Midimon. Don't know if the unit has anything on board to alter the response of individual sensors - it's a bit of a black box.
I'm using a Bidule group to control mine, so I guess I'll have to look into individual sensitivity tweaking for each sensor