Even before holding the shard, she is connected yes but none of that connection has prevented her from causing destruction, killing people, changing things. So your concern regarding too much connection via tapping to a shard would restrict that person! I think it will be all right. not a big issue. They can still function normally and get done what they needs to get done.
As for elend, well I agree that he had a strong connection to preservation too, in fact I had always thought his connection was stronger than Vin. While reading Mistborn, I had a feeling that vin is not the HoA because you know it’s Brandon... and there is always a twist... but I had suspected Elend. Reason is because he was always visited by misty leras, he witnessed a god die. I never suspected Sazed!!
But now that I think about it, I think Elend does not want to preserve the things as they are. He wanted to change the whole system. He was deeply troubled when he was emperor because he was doing the exact same things as all kings do instead of making the changes that he had dreamed of. So, may be we are wrong. He is not as connected to preservation as we thought.