Is the SBS C11F a 91 Ah or a 92 Ah battery?

Both numbers are correct, at different rates. EnerSys publishes 92 Ah at the 8-hour discharge rate and 91 Ah at the gentler 10-hour rate, and listings elsewhere pick one or the other. Size a string from the rate that matches your reserve-time requirement, and treat the one amp hour between them as the rounding it is rather than a difference between batteries.

Why pick the C11F over the PowerSafe V-FT 12V92F?

Same maker, same 92 Ah rating, different tiers. The C11F belongs to the SBS line, which carries EnerSys's 5-year term, a -40°F operating floor and the fast-charge cyclic duty TPPL is sold for; the 12V92F sits in the V-FT tier with a 4-year term and a -22°F floor at a lower price point. A stable, conditioned site with clean grid power lets the V-FT do the job for less; a site that cycles hard or freezes justifies the SBS.

What temperatures will the C11F tolerate?

EnerSys publishes an operating range of -40°F to +122°F and a recommended band of 68°F to 86°F, and the distinction matters. The wide range says where the battery functions; the narrow band is where it delivers its full published life, since heat above it accelerates aging in every lead-acid chemistry. Plan cooling toward the recommended band and treat the extremes as survivable, not free.