I spoke to Mojo, apparently its fine, all to do with the low / high speed compression on the new generation shocks. Particularly on the float R with the in built propedal. I may not have noticed before on my other shocks with manual switchable propedal as I always set the sag with the shock on full open so I guess that very high anti-bob compression tune wasnt that prevelant.
Meaning when a high speed load is acting on the shock it will move quickly as you’d expect (i.e a bump) but on a slow speed load (i.e a pedalling force or a slight shifting of weight is applied it has a high rate of compression damping slowing it down, so its not bobbing under pedalling, he said that this transition between high speed forces and low speed forces has increased a lot in the 2009 shocks onward. He said that the older generation shocks didnt do this so well.
I described to him in detail on the phone (twice !) the exact thing that is happening when I sit on the bike, and he basically said “yep, thats exactly what I would want to see happening, as it means its working perfectly”
So I am one happy camper now 😀