When I was diagnosed with CaP almost a year ago, I opted for radioactive seeds implanted in my prostate, brachtherapy. I unfortunately had a rather rocky recovery. I failed voiding trial after voiding trial..., 6 in a row. For the life of me I could not pee on my own whn the catheter was taken out. After 4 long months of learning to hate the catheter and urine leg bag, I sought another urologists opinion. He could not determine why I could not void. He said it almost never happens. towards the end of the appointment he mentioned the prostatic stent you mentioned. He had not used one and was not recommending it, just suggested I do my own due diligence. I went back to my urologist. He had no experience with The Spanner either and was not very supportive of the idea. I was so at the end of my rope with the d**n catheter and leg bag, that I pushed him to insert it in me. I am honestly glad I did. Voiding very well on my own, free of the catheter and dragging a bag full of urine around all the time. Pretty much have a normal life back. I did have some urgency and frequency when it was first inserted for about 6 days. I also experienced some burning at the tip of my penis while voiding. Again for about a week, when it went away. I wore the stent for nearly 5 weeks. having it taken out was not nearly as bad as I imagined it would be. For me, wearing the Spanner was markedly better than having to live with the catheter and leg Far better.
No way to know if your father would have the same outcomes, but I for one, was helped a good deal by it. it just seems more normal, a kinder option to the indwelling catheter. One man's opinion.
What ever your dad decides, best of luck.