IMHO...it totally depends on the people involved. If you are in COMPLETE agreement with this, lay out a clear set of ground rules...before anything takes place. Then you also need to make sure the other guy is okay with and understands all these ground rules. As long as you are all in agreement, and everyone is on the same page, it should be fine. But the three of you are the only ones who can really answer that question. If there is any apprehension on anyones part, don't do it.