I have said this before and I will say it again: if you wanna know more about ANY hack, find REAL CUSTOMERS and talk to them. This caution applies to ANY AND EVERY HACK, not only Krusty.
You should not believe in vouches of any kind, there are lots of fake accounts, paid vouches, vouches that have been given in exchange for free keys etc. Your only way to be safer / safeish is if you can talk to people who actually bought the hack and that have been using it for a while.
Just out of curiosity, every once in a while I message people asking about a specific hack they have vouched for. LOTS of times their reply is something like: "I never even used that cheat"... so that's my point.
Edit: forgot to give you an answer. I PERSONALLY wouldn't go for Krusty. If you search the forum, you will find lots of people reporting bans using Krusty. However, when you go to their thread, you will only find positive reviews (not to mention that the owner claims that its been UD for 3+ years, but literally every hack in the past year was detected at least once, including Krusty). When something is kinda shady, I opt to avoid it.
Mentions of Krusty bans can be found, FOR EXAMPLE, here: