I wouldn't discount the value of your BJ4 dude.
Sure the AE is cheaper, but so are some of the parts. You get more carbon fibre on the BJ, more anodised aluminium, it's got all the parts that most people usually 'option up' on their cars.
So for me the BJ4 still has its spot.
If the AE performs a lot differently to the BJ on the track, then maybe my comments will change. So this is based on specs at this stage.