ok that probably made no sense
new APG Fighter Varients
example
Roughrider
Steadfast Mount (Ex):replaces bravery
Armored Charger (Ex):replaces armor training 1
Mounted Mettle (Ex): replaces weapon training 1, 2, 3, and 4.
Leap from the Saddle (Ex):repalces armor training 2
Relentless Steed (Ex):replaces armor training 3.
Ride Them Down (Ex): replaces armor training 4.
Unavoidable Onslaught (Ex):replaces armor training 4.
Indomitable Steed (Ex): replaces armor mastery.
First Question
RAW you must take all of these abilites correct ? you can't for example choose to take armor training 1 instead of armoured charger ?
Second Question
Assuming your normally not allowed to would it be terribly overpowered if you were allowed to ?
For example
Fighter
Bravery
Armor training 1
Weapon training 1
armor training 2
weapon training 2
Relentless steed
weapon training 3
ride them down
unavoidable charge
weapon training 4
indomitable steed
weapon mastery
basically choosing when to start taking the variant abilities.
1) That's... a good question. The alternate class feature assume that you are a Fighter(alternate feature), so in progressing in the "Fighter" class, you have effectively replaced what you would have gained, as in "they no longer exist, this is what you get". I would say "Yes."
2) That is a very specific question to be asked of the DM whose game you are playing in. If there is no answer, assume "No"
1. You have to take the whole package. Don't have the book here, but I'm 99% sure it's explicitly stated.
2. Probably depends on what abilities. Talk to your DM. Some archetypes have some abilities better than the standard and some abilities weaker than standard to compensate - it'd be very easy to just pick the good ones and skip the worse ones.
Indeed.
APG p.72: 'When an archetype includes multiple class features, a character must take all of them—often blocking the character from ever gaining certain familiar class features, but replacing them with equally powerful options'.
fair enough about cherry picking
although what about getting a once off choice at which level you stop getting the core abilites and start getting the varient abilites ?
You must make the choice at level one. You can not mix and match. You are a variant fighter or you are not, you can not be both and you can not take the same class twice.
There is no way to only have some of the changes, you take them all or not at all.
As for cherry picking, the RAW clearly says you cannot do this, as the half-elf has already demonstrated.
However, the OP asked if it would be overpowered as a houserule to allow it. I believe that would be a mistake, unless you're absolutely sure the player to whom you offer this ability is very much non-munchkin.
Taken as a whole, we can build a good case that the entire list of substitutions for any one variant is roughly equivalent to the class abilities that are surrendered to receive those substitutions (sure, some variants are probably better than others, but let's assume that each whole variant is roughly a good/balanced trade-off).
Even if that assumption is true, it doesn't mean that any one variant ability is a good/balanced trade against the ability surrendered at that same level. One variant may have the fighter give up a powerful level 1 benefit for a weak variant benefit, but later at level 4 he may get a powerful benefit for only a weak fighter ability, so it breaks even.
Allowing cherry-picking means the player could skip the weak variant (keeping the strong fighter ability) and then gain the powerful variant later.
All the power and none of the weakness.
No trade-off.
Worse, another variant may be the exact reverse of thye first variant - so if you allow someone to play variant/variant, he could choose the powerful ability from one variant at level 1 and the powerful ability from the other variant at level 4, and never have to choose the weak abilities.
This stuff would be a munckin's dream. A power-gamer's heaven.
I would be very wary of it.
I might allow some cherry-picking, but only after careful consideration and on an exception basis.
They're archetypes instead of lists of alternate class abilities for a reason. They are meant to be a package.
Especially in those cases where one ability replaces several other abilities, or where a powerful ability replaces a weak one, but with the same build, a weak ability replaces a powerful one, balancing things out and merely shifting the class's focus.
But even if it's apparently a one-for-one deal with abilities that look like they replace something of equal power, you can unbalance things when not considering the big picture.