Now, here's my opinion in answer to your question whether you are too hard on Mr. Vance personally. When I look at how John Calvin refuted the semi-Pelagian views of Albertus Pighius in his magnificent work, [i]The Eternal Predestination of God[/i], your introductory remarks read like a "love letter"!
It is certainly true that Calvin and many who wrote in like style were too "harsh" in the eyes of many moderns today. Yet perhaps their negative assessment is more the result of a lack of a commitment to biblical "true truth" and/or a rejection of "absolutes" concerning the person and nature of the Triune God and the salvation of sinners. But whatever the reason, "schmoozing" and a "laissez faire" attitude concerning biblical/theological matters is the rigor of the day.
While contemporaries counsel, "You can't love others until you love yourself!", the Word of God in contradistinction declares, "You cannot love others unless you love God first and foremost!" (Matt 22:38). Neither the Lord Christ nor the Apostles made it a habit of "mincing words" when it came to defending the truth of God or the Gospel of grace. At the risk of sounding like the proverbial "broken record", the late Dr. John H. Gerstner was a man who exemplified this truth in that loved God and his neighbor so much that he refused to compromise the truth! (see the attached article).
Let me end my approval of what you have written thus far by quoting Martin Luther, who I think sums it up nicely:
"I am not permitted to let my love be so merciful as to tolerate and endure false doctrine. When faith and doctrine are concerned and endangered, neither love nor patience are in order.... when these are concerned, neither toleration nor mercy are in order, but only anger, dispute, and destruction -- to be sure, only with the Word of God as our weapon." - Martin Luther
May God guide you, grant you wisdom and perseverance in this endeavor. But more so, may He fill your heart with more love for Him and His immutable truth so that your light may shine bright as the noon day sun.
One Puritan said "Showing mercy to the wolf is showing cruelty to the sheep."