Thanks to you all for your helpful comments. I won't attempt to reply 'individually', but will hopefully touch on the main points raised.
It is a little difficult to accurately determine the technical benefits of one system compared with the other. Apart from anything else, I'm sure that they have both brought in upgraded versions (I know that Ablatherm has), and I imagine that they are pretty much 'toe to toe' in attempting to maintain technical equivalence.
In the end, I think we have to accept that whichever system a particular doctor is using, he/she will make a good case for that system being the better one! I'm inclined to think that maybe they are both much of a muchness, but I am interested to find out any significant differences, which is why I posted the question.
You are all so right that the important thing - the absolutely essential thing - is that the operator has oodles of experience. Both Ablatherm and Sonablate are available at a number of centres in the UK, but so far the people I have spoken with have not carried out very large numbers of the treatment. The largest I have found so far is about 100 (Ablatherm) over a period of about three years, which I guess isn't bad, but doesn't begin to compare with some of the people in mainland Europe using Ablatherm.
Mostly, the HIFU centres in the UK are only offering the treatment privately, but I believe it is possible to obtain treatment on the National Health Service in one or two places, which I'm busy following up. However, when it comes to the crunch, I would rather pay money (a lot of it!) for private treatment with someone with extensive experience, rather than free-of-charge treatment by someone with possibly considerably less experience.
There is a HIFU study in London at the moment (at the Royal Marsden I believe), but I think this is based on using HIFU as a salvage procedure. There is another trial using HIFU as a primary treatment, but I am not eligible for this as I am on hormone treatment for three months. Again, if I had been eligible, I would need to be really confident that this trial is involving people with considerable experience, and I think that is maybe slightly doubtful?
In mainland Europe, Ablatherm has been used for about 12 years, although I think it's fair to say that the experience in the earlier years was fairly limited and possibly not particularly successful (there must have been quite a steep learning curve going on at the time). Things have moved on apace.
Ablatherm claimed (in 2008) that there had been over 15,000 treatments with their equipment worldwide, but I think the majority of those were within Europe. There have been a number of papers published over the years by users of both Ablatherm and Sonablate in Europe and, generally speaking, those from the latter years have tended to assess the treatment as being comparable with non-surgical treatments, in terms of shorter term morbidity and medium-term oncological outcomes. What is currently not available are hard data on longer term oncological outcomes, particularly anything involving RCTs and peergroup review.
I am leaning towards Ablatherm at the moment, if only for the reason we all consider to be very important: operator experience. There is a guy called Dr Chris D'Hont whose clinic is in Antwerp, Belgium, who has carried out over 700 Ablatherm treatments to date with, apparently, a pretty good degree of success. I'm attracted towards his clinic because of the number of treatments he performed. I have a paper written by him which contains useful and encouraging figures, but of course this has not been peergroup reviewed, so one has to hope that it is accurate. It was written in Dutch, and I used the Google translation facility to turn it into English. The resulting translation is pretty amazing for a computer, but there is still a certain amount of gobbledygook remaining, although one can get a pretty good idea of what is being said.
I came to hear about him via someone from the West Country in the UK who was treated in Antwerp in 2003. He was very happy with everything to do with the treatment, and with his subsequent positive progress. His wife is a really enthusiastic proponent of HIFU with Chris D'Hont, and has pointed possibly 200 men from around the world towards his clinic over the past few years. She reckons that's probably a hundred or so of those people have actually had treatment there. She has a considerable amount of mail from 'happy customers'.
I'm planning to travel to see Chris D'Hont sometime within the next couple of weeks for a preliminary consultation. Of course, much will depend on the results of that meeting, as I tend to go a lot on the feeling I get about someone when I meet them. I certainly haven't decided not to go the Sonablate route (thus my posting), and I shall be contacting more people in the UK about this during the next few weeks. Whichever direction I go, I can't have HIFU until towards the end of September at the earliest, because I am on a three-month period of hormone treatment.
One final question. I keep on reading at this forum that people chose radical prostatectomy because they wanted 'final pathology'. I'm not really clear what this means. I can understand that once the prostate has been removed, pathology will reveal the extent of the cancer, which will sometimes prove to be more than was indicated by biopsy. That must be of interest to the medical profession, but I'm not sure how it helps the patient. Therefore, I have to assume that pathological examination also includes tissue removed from areas around the prostate during the surgery, which will help to indicate if there are tumours beyond the capsule. This sounds well and good, and obviously is of considerable benefit if the surgeon is able to identify areas of tumour outside the capsule and remove them at the time of surgery. However, I was told by my consultant that during the surgical procedure, it would probably not be possible to identify micro-metastatic excursions, so I obtained the impression that there would still be an element of doubt remaining. Maybe someone can be kind enough to clarify things for me.
Once again, thanks your input.