The JTech seatpost is new and you will see a wrap of insulation tape 1mm from where it disappears at the clamp so I can see if it slips down. It is well greased but with a lot of torque I think I have got it immobile. At least, a one mile test ride didn't budge it.
Have you thought of using the gritty grease used in carbon fibre seat tubes? It might be a better compromise than regular grease and lots of torque and/or multiple clamps.