We have had members who have had the two week SABR, but people with successful outcomes tend not to hang around on the forum, they just get on with their lives. So you may not get a response from anyone who has had the treatment.
SABR as a primary treatment, as a clinical trial, has been around for about 10 years. That trial has reported and it has been very favourable. At the ten year mark it is as good as any other treatment, so there is no reason to suppose at the 20 or 30 year mark the effectiveness will drop suddenly.
The reported side effects of SABR are minor. Whereas the reported side effects of surgery can be quite severe, though that is probably in less than half the people who have had surgery.
In the end only you can decide what risks and side effects are important to you.