Richard you are absolutely right , in any sort of steady breeze the J class and their modern replicas are awe inspiring up close , the power ! And they require a well drilled crew to get the best out of them, I would avoid standing too close to the headsail sheets or turning blocks by choice . Down below they have all had buckets spent on them as well, the current crews dont have a rough hammock in the focsle any more -its all air con and beautiful meals . Sailmakers have done well out of the renewal of interest in these lovely craft too, one sail order is a magnitude of work that a few years ago was hard to imagine, of course with modern synthetic cloths and running rigging the rig loads have skyrocketed and so above deck it has to be redesigned to allow for this.
Talking of the Broads -I shall be afloat on them in three weeks yippee -hopefully your summer will last.