
John Mangrum |

It was written for 3.5, so the Fast progression track is the closest to the mark. However, the 3E and PF XP tracks aren't identical, so conversion can produce some unintended results. It's entirely possible for thorough PCs to end House of the Beast a full level ahead of the curve, and if that happens, they'll probably remain a level ahead throughout The Jackal's Price. By the end of The End of Eternity, however, XP progression normalizes again and PCs should remain on target through the end of the campaign.
Personally, I'm running LoF on the Medium XP track. This smooths out the House of the Beast bump, at the cost of having to add a few side missions to Howl of the Carrion King and a widening XP gap that starts to kick in during The End of Eternity. (I'm filling that gap with side adventures; I inserted Broken Chains into the middle of The Jackal's Price, which has put my PCs a level ahead of the curve for the moment.) If you run LoF on the Medium track, I also recommend seeking out the "Designer's Cut" of The End of Eternity; it adds a lot of XP opportunities to the sandbox, which makes it fit the Medium track rather well.

Olwen |

I updated Legacy of Fire to Pathfinder and played it with the medium XP track and a 15-point buy. Since Pathfinder characters tend to be more powerful than 3.5 PCs, it worked very well. My players were reasonably experienced at the time and there were still some tense moments. It may be a problem, though, if your players aren't very experienced. In that case I'd go for the fast track, or just drop XP and level up the PCs when it's warranted by the story.

eakratz |
I'm just having my PCs level up at certain milestones. Also, a caveat I just encountered last night. We just finished The Jackals Price and the players decided to take the scroll to the temple from the set piece and have the lamassu guard it. With his spell like abilities, I believe they found a way to avoid The Impossible Eye altogether. Doesn't affect me much but it could throw things off.

Alex Cunningham |

I'm just having my PCs level up at certain milestones. Also, a caveat I just encountered last night. We just finished The Jackals Price and the players decided to take the scroll to the temple from the set piece and have the lamassu guard it. With his spell like abilities, I believe they found a way to avoid The Impossible Eye altogether. Doesn't affect me much but it could throw things off.
I have been doing the same. My group has the most fun when any _one_ of them is too weak to take on any challenge alone, but together they are just slightly OP for the encounter. I pretty much just level them up one session before they "need" to; no fuss, no muss.