A few weeks into my Jodan odyssey and i've come to realise a few things. Primarily that its going to be a long and relatively lonely road!
I feel like an absolute beginner again. I've lost kendo strength and upper body muscle mass (not that I had much to start with) due to my time away injured. This combined with the need for katate techniques/tenouchi means I need to work on my left shoulder, tricep and forearm conditioning. The change in footwork is also like a step back to my early years, I have no push drive from the right or fumikomi from the left foot. This will hopefully come with time.
Yet I am very heartened by the support my sensei and peers have given me with this change in direction. All those with experience in Jodan have offered advice which I'm trying to build into my practice. However, after three weeks i'm still flailing around like drunk fly fisherman, it feels like i'm moving through treacle.
After contemplating the situation, I think what saddens me the most is letting go of what I could previously do with chudan. Through this kamae I could at least give seniors two or three grades higher a half decent fight..... now I'm back to slo-motion cutting with poor threat level. But I also feel quite excited about learning something different.
After trawling the usual web and youtube sources (i.e. Chiba sensei), I found this page which is pretty informative http://www.kinsho.hu/p/jodan.html
If anyone out there has studied Jodan without a specialist teacher then I'd be interested to hear about your experiences :)