I've done one-ways a number of times (by far the best use of free days, IMO) and have never had a problem. Just like a regular rental. However, I do note that all of my one-ways have been out of large, corporate-owned locations (e.g., with EA/ES service). I strongly bet that you'd have issues if it was a franchise or even smaller location. Since you are renting from DEN, I don't think you'd have any issues.