Well I added one more cross support between the pier and my house - to pre-stress the pier and minimise vibration.
Bottom line is its quite excellent now
I realise the floor connection was more important than I gave credence too. Whilst my design had great load bearing capability, it did not provide adequate rigidity from minute vibration. This is probably where tripod legs on portable piers work well.
But its on a woodedn deck anyway, so there is only so much I can do to stop vibration. Whack the base hard now - like a solid kick that would fling a tripod five feet - and my pier settles down under 3 seconds. A lesser knock has no vibration after a second.
So, as long as I sit still on my comfy adjustable bar stool (with back support) everything is rock solid.
Now just the trimming and painting (artwork) remains. Will take some piccys and upload soon, it was a fun and frustrating project!