Not needing to pay 4 life to survive has been really nice, and the life gain has been incredible. I think Vanguard is def good, but the 4/4 lifelinking mode was def underrated by me at first and has been super great in practice. Vanguard has still been good--when you can pay the 4 life, it's great!--but there are too many fast decks to chop off 4 life too often to say that's def better.
If it's asking for 8-12 life and I'm paying, then it's the right choice, right? Seems like almost always having control over when to activate is probably better than potentially not having energy and this dying, or dying after the first activation, especially for an aggressive 2 drop where late game activations are way less important.
I think that this is solid. The threat of activation can make blocking decisions awkward for an opponent, and if my opponent is going to try to remove it, I think I'm fine trading 4 life for the average removal spell. I may kick Lone Missionary back out again for this.
This is not a comment about whether that's a good cut or not, but the thought of cutting a creature that gains you 4 life for one that can lose you 4 life is kinda funny.