Tiering the Pathfinder Classes - Gunslinger, Slayer, Swashbuckler and Shifter

[Kurald Galain]

Rerolling failed saves is a pretty valuable defense,

Yes it is, but rerolling one or two saves per day at level fifteen is not a particularly big deal. Gunslinger grit just isn't very plentiful.

The capstone, by RAW, can even augment Cheat Death

Let's see. The first hit that would kill you instead leaves you at 1 hp and 1 grit; the second one leaves you at 1 hp and 0 grit; and then the third hit kills you because you were at 1 hp. So a single full attack of a high-CR monster can still kill you. That's a decent combo but not particularly game-breaking or tier-raising.