I know you always shy away from the "two options for one" question, but having the fillet'r "fail" if the result is not "correct" may be good for someone that doesnt know how to do this stuff. ie; If the fillet'r goes ahead and makes this surface that needs to be low level trimmed, the newb will make a model that doesnt work and wont know why. Danny for instance, may want this and know when/how to fix things up. Burr for instance, will need multiple posts from Michael, explaining tangency and then starting from scratch instead of figuriung out something is wrong from the begining. Being able to enable or disable the fillet'rs "ability" could suit the "easy for beginer" mission of MoI. (advocate is to many options becomes rhino).