Only MC + GT6 + NEI needs just 1GB of RAM and runs fine on a 1.1GHz Intel Quadcore Processor with Integrated Graphics. Fastcraft and Optifine can help too.
I just use the same naming scheme for "Electric Units" in GT6 and "Energy Units" in IC2, they also are 1:1 conversion ratio and essentially the same thing.
Rubber Trees do exist in GT6, just in different Biomes, and you can get Resin from those too with a slightly different mechanic. You can put a Leather Bag for collecting the Resin out of the Holes semi-automatically.
Things exist in GT6 that copy IC2 Stuff in order to NOT depend on IC2.