LTC4412 - Pricey
OnSemi/Fairchild has a bunch of "advanced load switches" which could be used I think and are not tooooo expensive
These are all Enable Active High, with reverse blocking, without output discharge and can do at least 1A.
Could be used instead of the Pfet and keep the schottky on the ext power input, but have to invert the enable.
FPF2495 - sounds nice, but it's a CSP/BGA package, only 9 balls though with 1 center and all the others on the perimeter, so probably not totally evil, in/out up to 28v, logic pins to 6v; active high.
States reverse current blocked in ON state ("True Reverse Current Blocking")FPF2195, FPF2193, FPF2194 - like the 2495 but only 5.5v and in a 6 ball CSP so could be "easy" enough to do with hot air since all the balls are on the perimeter; active high.
Reverse current blocked in ON State, "If the switch is turned on and the output voltage is greater than input voltage, [...] turns off the switch",
when output is within 50mV higher than input reverse current can flow in ON state (50mV/Ron), but at worst is less than an Amp and with only 50mV I would expect it to be very brief
FPF2123, FPF2124, FPF2125 - adjustable current limit, no discharge, reverse blocking, Enable active high, 150mR, up to 1.5A, wide input voltage range, and it's in SOT23-5.
Does not say if reverse current blocked in ON state.FPF2165R - MLP with center pad, much like the 2123 in capability I think
does not block reverse in ON stateFPF2163, FPF2164, FPF2165 - similar 2165R
does not block reverse in ON stateFPF2595 - this is a 12 ball CSP, too much for me
These are active low, not much choice here...
FPF2300, FPF2302, FPF2303 - SO8 or MLP; dual channel active low
does not block reverse in ON stateFPF2895 - 24 ball CSP, enough said