The decision on what to go with has to be yours. You do not give your staging but both Surgery and HIFU work best if your cancer is confined to the Prostate capsule - suggest you discuss with surgeon. A friend of mine had 'open' surgery and he did need a blood transfusion during his op which otherwise went ahead without problem. So it can happen but by no means necessarily so. A lot more is known about surgery, potential adverse side effects and long term outcomes.
HIFU, is still regarded as experimental in the UK because there is less known about long term outcomes. Within the NHS It is usually given as part of a trial. It has more often been used as a salvage treatment for failed radiotherapy in the UK rather than as a primary treatment which is the reason why I had it. In need HIFU can be repeated. With HIFU outcomes have been found to be better if the tumours are small and confined to one side of the Prostate.
Different men can respond in different ways and to varying degrees to all treatments but generally men who have HIFU recover from the procedure far more quickly than with open surgery. I was walking round London a couple of hours after the procedure. In fact I found it easier to walk or stand rather than sit down. The catheter was in for a week post op and it was much more comfortable after is was removed. I reckon there was about a teaspoonful of blood in my urine the first time I had a pee after the catheter was removed and thereafter it was as though I had not had the procedure in all respects, although previous HT/RT had caused ED so I can't comment on this aspect. However, some men experience a blockage that requires further catheterizing and/or other side effects which a Google search will show. So I was one of the lucky ones.
I recommend that you download or get a copy of the "Tookit" from the publications section of this charity. This details a lot about PCa and treatments.
Wish you well and do let us know how you get on.