Hi Martin, I already have a 2005 AHD Limited Edition 85 which I picked up for £400 last summer replace an iSonic 145. Being a Bewl sailor I need a light wind planer to maximise TOW in the often fickle winds we get there.
I found the difference in the light wind early planing performance between the AHD and the UltraSonic is marginal. In fact the AHD is easier to get planing because I don't have to bear it off the wind as much. Nevertheless the USonic is a very good performer, but the the AHD is so similar, plus it also feels more composed when the wind gets up, that I can't justify the £1k price difference between them. So regrettably the USonic will have to go, but if weren't for the AHD it would be a keeper.
I wish you good sailing with your USonic, I'm sure you will be amazed by its performance. BTW I found it's worth investing in a bigger fin (62/65cm) to maximise its light wind potential, the 58cm fin supplied is fine when the wind gets up.
I have the full carbon version Ultrasonic which I would consider selling for a good offer. It has been sailed half a dozen times and it is in excellent condition, complete with a Prolimit bag. There is a choice of 5 fins from 55cm to 65cm. Please contact me if you are interested.