My family is Shia...our nikkahs are a little bit different from yours. In Sunni nikkahs, the marriage is made official by the bride and groom accepting the terms of the nikkahnama. In Shia ceremonies, the bride and groom merely give the maulana permission to perform the nikkah according to the terms of the nikkahnama, and then the maulana recites some verses in Arabic that "officially" marry you. I'm not sure, but I don't think laypeople technically have the authority to do that...
I'm Sunni but I wouldn't feel comfortable having a layperson such as family elder doing my nikah, I prefer the idea of someone 'neutral' from outside of either family (tho my hubbys family isn't Muslim anyway) and who has proper Islamic knowledge and knows all the ins and outs of the procedure and all the etiquettes. I have a few elder family members who think they're very Islamic and they have beard etc. but their Islam in 90% cultural and I'd cringe at the thought of them giving a speech that implies I should blindly obey my husband etc. rather than the proper Islamic idea of marriage that compares the spouses to 'garments' that compliment each other :)