The KMS 105 is the best mic I have in my live vocal mic collection - no question - but it isn't always the mic I use! There are many factors which determine which mic to use in any given situation and on any given vocalist.
I would be more inclined to use it on female, or subtle male vocalists where on-stage levels are not too high.
It's a sensitive mic, so you do need to be careful with monitor positioning and levels as has been said. I would not recommend a feedback suppressor, not even as a last resort, (like putting retreads on a Bentley) you need to work on monitor positioning, levels and vocal technique.
I always recommend auditioning mics before buying them. What suits one person may not suit another.