On topic of BC gears (Or TE for that matter)
Currently BC registers its gears in ore dictionary but does not use oreDict gears in recipes.
Logistics pipes only uses BC gears
TE I cannot remember (I think it uses oreDict)
Forestry uses oreDict
Foundry uses oreDict and has excelent GT support
Railcraft Registers its Steel/Iron gears but doesnt use oreDict in recipes
ExtraBees/Trees only looks to buildcraft gears
Thats all I can think of off the top of my head.
Its a plague of people registering items then not using oreDict.
The best solution is to get minetweaker, remove BC/RC/Forestry/Misc... gears from the ore dictionary, remove their crafting recipes, then rewrite the recipes to use ore dictionary gears.
That is what I have done for my modpack I am running at home.
BC - Energy values reworked, recipes completely rebalanced
MFR - Recipes partially rebalanced (GT Recipe support seems to have died) *This is still a work in progress and will have some major energy rebalancing soon
Logistics pipes - I havn't got around to tackling this yet, im hoping the devs will fix it before I have to
ProjectRed - Red alloy now uses GT alloy and there is recycling macerator recipes included (Also screwdriver added to oredict for crafting)
Forestry - Just normal configs need tweaking because Sengir uses oredict and recipes just work for once
Railcraft - Redo recipes for anything that requires a gear. *More will probably be done later might disable their steel tools although I like watching people make shitty inferior steel tools not wanting to "Waste" 2 iron to make the rods early game **Still need to remove rolling machine
Thaumcraft - Everything works pretty ok and decently balanced
ArsMagica2 - Everything works pretty ok, BWG4 and a config tweak make this mod very slow and very endgame to progress through. (Nice compared to the normal cheese mode that is acheiveable)
Foundry - GT Recipes, OreDict, works like a charm, I have zinc and nickel in worldgen because they seem very rare
Also... A suggestion: Add Steel plate crafting to the metal former. Although it can do the job of alot of other GT machines it doesn't do the job very well. Its a sort of "Jack of all trades, master of none" so the ability for it to produce basic bits of everything may be usefull early on but an ultimate waste of resources. Leaving a short term gain vs sustainable production of everything a choice the player can make, but the metal former is too weak of a block to do that without steel plate crafting.