DISCUSSION QUESTION: What Is The Difference Between The "Tests of Genuineness" and "Means of Salvation" Views?

We ended class this past Tuesday with this question briefly brought up. For those who are (or lean towards) Calvinists and who thus have a strong view of God's final preservation of all His chosen people--that is, that no true believers will fall away and perish--the two options for understanding the warnings are the Tests of Genuineness view (Wayne Grudem, etc.) and the Means of Salvation view (Schreiner & Caneday, etc.). So a crucial question is, what are the legitimate differences between these two interpretations of the warning passages? On the other hand, what common ground and similarities are there between them? Does it matter--practically--which one we hold to? We'll discuss this more in class, but I'd love to start some dialogue now in the comments section: what differences or similarities do you see between these two views?