Would gestalt fix a geomancer?

[Mr.Kraken]

Most people complain that the geomancer is underpowered because of its entry pre-requisites (you must be able to use 2nd level arcane and divine magic, deliberately lowering your caster level).

I'm planning on having a fey-descended character start as bard//cleric and then move on to geomancer. Would being an arcane/divine caster gestalt fix the geomancer as a PrC?

[Flickerdart]

It wouldn't fix it. It would make it not actively nerf you, but its benefits are so mediocre that taking 10 levels of it is basically the same as just taking 10 levels in one of the casting base classes you used to enter.

[Forrestfire]

Overall, Geomancer becomes a generically neat theurge at that point, but it's probably more useful to just keep Bard going and find a better Cleric PrC, unless you're actively going for Drift or Spell Versatility. It's fairly neat in gestalt if you do want either of those, though.

The only especially useful things I've seen done with Geomancer is combining it with something that abuses Spell Versatility for some sort of shenanigans. For example, Paladin 4/Wizard 1 with Sanctum Spell to qualify for the prestige class, then the Battle Blessing feat. You can cast all your spells as Paladin spells at that point, letting you freely quicken them without costing anything extra. It loses four levels of wizard casting, though. Another example build that usefully uses Geomancer might be to like Paladin of [evil alignment] 4/Wizard 1/Geomancer 1/Ur-Priest 2/Geomancer +9, using your fast-progression in divine spells to keep up with other casters, and casting your Ur-Priest spells as swift actions. Sublime Chord could also be used pretty well, going Paladin of [chaotic alignment] 4/Bard 1/Geomancer 5/Sublime Chord 1/Geomancer +5/something else 4, grabbing 9th-level arcanes with again, free quickens.

[Mr.Kraken]

...unless you're actively going for Drift or Spell Versatility.

That's exactly what I'm going for, unless there's another way to get a Charisma-based cleric. I know there's Dynamic Priest, but I haven't found anything (in 3.5) that switches the cleric's spell DC to Charisma.

[ExLibrisMortis]

Geomancer has a nice power level, in my opinion. Geo-gishing is pretty nice, if you can get your DM to rule that battle blessing changes a paladin spellcasting parameter. Illumian paladin 4/sorcerer 1/geomancer 10/abjurant champion 5.

In gestalt, you can do a similar thing, except with full caster level and full paladin levels. E.g. paladin 20//sorcerer 5/geomancer 10/zhentarim skymage 5. Get your DM to stack paladin mount and skymage mount (pay a feat or something, a cool way to do it is to add cha to paladin mount HD), use the same battle blessing ruling, and on top of that you ignore arcane spell failure chance. Good way to go for a dragon-rider, if you refluff drift to some draconic things.

None of that makes geomancer an incantatrix, though.