Should we mind either way if we have one (or more than one) moderators in common?
I believe that we should seek out moderators regardless of their involvement in other sites. I believe that this site's independence is the responsibility of the community and can be achieved through the community becoming involved in developing this as an independent site.
Furthermore, the purpose of moderators is simply to become involved in the community and to help enforce rules that the community has established. I don't see any conflict of interest whatsoever with having moderators here that are also moderators at Christianity.SE.
Instead, I believe moderators should be chosen based on:
How invested they are in the success of this site
We should expect and seek out moderators that want to see this site succeed. We want moderators who want to be here and are willing to commit to their
We need people who understand how the StackOverflow community works.
We want moderators who are available. If we choose a moderator who is only going to be around a small portion of the time, clearly, they are not going to do well as a moderator. They will not help support the community.
This is, interestingly, related directly to the first criteria. If a person is available, they'll be heavily invested. The more involved they are, the more invested they are (and vice versa).
This may seem like and odd qualification, but we want people who are moderate (not commonly involved in arguments and not quick to anger) in order to moderate (perform the functions of moderation).*
This is crucial since the most important aspect of moderation is communication.
Given this criteria, I believe that we should seek out the best qualified candidate regardless of their other responsibilities. Furthermore, I believe that it's up to each candidate to determine whether they are capable of handling the work load of moderating two sites.
* gotta love homonyms.
Full disclosure: I have a vested interest in this position, but yet I still stand by it's validity
I think this would depend on the interest of the person in question. The general principal would run the other way. Having moderators with experience on other sites would be one of
your our most valuable assets.
Before making a call about who to propose for consideration you should interview them to find out what their interests are and whether their commitment to the site and ideas about where it should go are likely to represent yours and the communities. StackExchange should also consider this, but they also have some other data to go on such as their involvement in baby-sitting the moderators in their previous work.
Another point is that any good moderator is going to be a representative of the community. They can have their own ideas (I for one do!) but their job is both listen as well as communicate, lobby for support of good ideas, figure out what community consensus is in the end, then support that direction whether it was exactly their idea or not. You want to pick people that are a track record of being good at this.
Lastly, because these sites are likely to have some cross over users and scope issues, having cross-over mods would help facilitate the communication between communities. Understanding a site scope takes a good deal of participation and investment of time. You want people moderating here that at the very least are active enough to have a good working understanding of what the scope of C.SE is or is not.
These are my honest opinions. For full disclosure, I have just accepted a nomination to be considered as a pro-tem mod here if SE is so inclined, and yes I am serving as a pro-tem mod on C.SE.