Hi Harold
There are basically only 2 things that ever go wrong: (1) the adhesives don't work well and therefore the hairline lifts a bit. This seems to happen in about a third of new installations; and (2) much more rarely, the adhesive causes skin irritation or a rash.
If you opt for a hairstyle where the front hairline is covered up, the first is manageable - if you get lift you just glue it back down. But that wouldn't work for an exposed hairstyle. In the case of the second problem, you could check for any skin issues by doing a skin test beforehand - get your salon to put a bit of whatever adhesive they plan to use on your scalp for a few days, and check that it doesn't cause any bad reaction.
Are you going with people who will know that you are wearing a system, or are you trying to keep it private?