Look into Multiworld.
http://www.curse.com/mc-mods/minecraft/multiworld
What it should do (I will be playing with it, but have not yet) is that anything you could set a server's overworld to can be used as a dimension.
With that said, compare the concept of world-types to biomes for a normal world:
Biomes, like Extreme Hills, or plains, or giant redwoods, or rainbow trees, all appear together. World types, such as realistic terrain generation, or ATG, change how the landscape works, without necesarily changing the biome generation.
Vanilla default_1_1 uses biome information to generate one type of world; it excludes jungles, mesas, mutants, etc. Vanilla default uses the same information, and more biomes, to generate hillier terrain, and then adds in even more biomes that are hillier yet. (1.1 to 164 used one set of rules for interpreting the meaning of biome base height and variation; 1.1 had a bug in the extreme hills. 172+ use a different set of rules that makes the same numbers hillier, and then add in the mutants, most of which are hillier than the base).
ATG uses a different set of rules to define ground levels, and then identifies climate zones from that; then there's a table for climate zones to biomes. That's not too much different from 17x's "biomes have climate zones, and worldgen lays out climate zones" -- heck, ClimateControl does something similar as well, but without overriding the worldtype.
I don't know how the BoP worldtype, or RTG worldtype work exactly, but again, RTG uses a different ruleset for laying out where the terrain goes (big change to rivers), or for turning the biome data numbers into landscape.
The issue is that mods like Biomes o Plenty, in addition to providing new biomes, also provide a new worldtype because their biomes aren't supposed to look right in the default worldtype; so right away, trying to use amplified means that they really won't work right. And if another worldtype+biome mod is in use -- Enhanced Biomes, I believe, also does the same thing -- then you are guranteeing that one of the two have to have their biomes not-quite-right.
But that's a bit extreme -- EB and BoP both add so many that I don't think you can use both.
(... and, why didn't Mojang include a default_1_6_4 generator for people who wanted to use the 125-164 seeds/landscapes and no mesas, like they had a default_1_1 generator for people who wanted the 1.0/1.1 seeds and old pandora-style extreme hills?)