I think the primary reason you should avoid becoming a 5 point Calvinist is because it starts with a faulty doctrine of God. It starts with a doctrine of God that does not start where the Bible starts; it starts with a conception of God that is philosophical and not revelational. It only moves to the revelational after it has first conceived of God philosophically. Most 5 point Calvinists appeal to Aristotelian categories and Thomas Aquinas’ synthesis of Aristotle’s categories to provide a grammar for speaking of God. The problem with doing this is that God is, when philosophically conceived first, emphasized as a singularity, a philosophical monad and thus this approach struggles with coming to terms with the fact that God is personal, relational, and Triune. If God is emphasized as a singularity, and a philosophical monad, then the way this kind of God, who must remain unmoved by his creation, comes to relate to his creation through static impersonal decrees and through secondary causation built into creation itself. Ultimately, we are presented with a God in this view, that is sub-personal, and relates to his creation in Law-like fashion.
It is true, 5 point Calvinists, many, in the history and contemporaneously, have sought to overcome this kind of impersonalness of God, so conceived, through a warm hearted piety; but that is not what is under consideration here. What is under consideration here—by way of theological taxis (order)—is whether or not the underlying doctrine of God that stands behind said warm hearted modes of 5 point Calvinism actually is able to fund this pietism in a way that is corollary with the background doctrine and procrustean bed it is built upon. I would assert that it is not corollary, and thus no matter how hard someone tries to be a pious 5 point Calvinist, there will always be this thread of a Law-like God woven through their piety that will eventually bleed through into their teaching, preaching, and practice. If this is the case, and I think it is, why not abandoned this kind of Calvinism for a version that starts where God starts, in his Son, as the Son of the Father through the communing life of the Holy Spirit. You could throw your hat in with us Evangelical Calvinists … as a matter of fact, why don’t you?