I had the 5-shot TopGun course as a primary treatment last May, specifically to take advantage of the enhanced accuracy to avoid loops of bowel, which had made traditional RT too risky in terms of collateral damage. I didn't have any spacer gel. My local oncologist was of the view that 5-shot treatment would become the norm, as funding allowed.
The treatment was pretty much a breeze. I had maybe 2 days in the week after treatment finished of not venturing far from a loo, but that was it.
Has it worked? Who knows. PSA is undetectable well after my HT has finished and washed through, so I guess it's 'so far, so good.' I'm happy with my decision, which is all you can hope for.
As you will see from numerous posts here, it's somewhat unusual for the RT itself to cause major problems but very common for the companion HT to produce inconvenient side effects.
Best of luck on whatever road you decide to travel.