My understanding:

Kishan published a study in The Lancet this April https://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(25)00034-8/abstract
UCLA put out a press release describing the work:

"A new large-scale study co-led by UCLA Health Jonsson Comprehensive Cancer Center investigators provides the strongest evidence yet that a shorter, standard-dose course radiation treatment is just as effective as conventional radiotherapy for prostate cancer, without compromising the safety of patients."
https://www.uclahealth.org/news/release/study-confirms-safety-and-efficacy-higher-dose-per-day
Keep in mind: for patients with localised prostate cancer.

For those who may still believe a shorter course of treatment must be more dangerous: The study distinguished between two types of shorter course treatment. Isodose MHFRT, and Dose-escalated MHFRT.

"Isodose MHFRT", apparently, means higher dose per treatment, less number of treatments compared to the formerly standard 38 days, less overall dose, but equivalent "biologically equivalent dose".

"Dose escalated MHFRT", apparently, means higher dose per treatment, less number of treatments compared to the formerly standard 38 or so days, less overall dose, but higher "biologically equivalent dose".

Biologically equivalent dose means a lower overall dose that is theoretically and observationally equivalent to the higher total doses formerly delivered over more sessions.

The study found that isodose MHFRT was as effective with no worse side effects. Dose escalated MHFRT had worse side effects.

The Kishan et.al. "Interpretation" of their study, as published in The Lancet:

"Isodose MHFRT and dose-escalated MHFRT both have similar efficacy compared with CFRT, but dose-escalated MHFRT is associated with higher physician-scored and patient-reported bowel toxicity. Isodose regimens, eg, 60 Gy in 20 fractions, should be the standard MHFRT regimen for localised prostate cancer."

Re: which machine?

The machine used for my recent 20 session RT was the Ethos Hypersight. It has cone beam CT imaging and a certain amount of ability to respond to daily changes observed by its superior imaging. It can, to a certain extent, tweak that days radiation plan. It has capabilities the operators in my case didn't use as well. I think it can also interrupt beam delivery when it detects too much movement of its target. Whatever it uses to aim and deliver the radiation is much smaller than some of the huge gantry things a lot of other machines have. It can change the direction the beam comes from very rapidly, which shortens the time a patient has to be motionless on the table.

I think Kishan is a big proponent of MRI-Linac.

The Prostox test sounds to me like it could be a big help for you to make a decision. Kishan was a major player in its development. Some patients develop more side effects with some RT treatments than others, and the test tries to predict what will happen.