You should always be concerned when it comes to any type of bot. It's a risk you take though. I am sure anyone you ask will tell you the same thing, dont turn it on and go on vacation for a week. Use it, check in on it, do guild chats, talk to other users, make yourself as human as possible.
I have been using it for weeks now, and never been caught. Have 3 toons at 450 fishing, 1 toon finished all the Dal coins achievement, and in my spare time fishing for the damn rat. Although Mr Fish It is not working 100% in the sewers for me.