Yes the image is comperable to the SD9 in bright light or outdoor when it comes to sharpness. But the HF100 shows less compression artifacts and there is something with skin tones and detailing that really appeals to me on the HF100.
I have always been sceptical about the upscaling done from the small 3CCD chips in the SD9. And the resolution results from the CCI review shows that Panasonic has only been partially sucsessful with this.
I am sure you will be impressed with the picture quality Rhubarbe, but since you where not to happy with the physical handling of the SD9 (you are an upright camcorder fan

), then the the HF100 will be no better at all in that respect.
Dont get me wrong here. The SD9 is a great choice if you want the best portabillity for outdoor shooting. The battery life is better and as stated the image quality is quite good. And if you are on a tight budget then it is about one third cheaper than the HF100. But do remember that the SD9 need lighting. It is REALLY bad in low light. In my view useless.
I think the SD5 is the best choice if you want a very good camcorder for less money. If you can find this one for less then £350,- then it is a great buy. Almost equal to the SD9 and much cheaper.