I have both the nanotech 5600 65c and the 6200 a-specs which I use in offroad 1/8th (2x2s). I use LRP packs in mod touring car.
The A-Specs are definitely better than the standard nanotechs. They feel more punchy and the runtimes are longer. The standard packs started to puff after 20 cycles whereas the a-specs have no sign of puff after 50+ cycles.
My advice would be go for SMC or some other major brand for mod touring but if you have to go for nanotechs then at least go for a-specs.