Iirc the Basic Teins are more expensive than the BC, and again iirc the Teins are only height adjustable and use your own top mounts.. Where the BC are fully height,dampner, corner weight, adjustable and use there own top hats and are camber adjustable at the front... And pillow ball all around.. So quite a lot more for same or less money..
Even if the Teins were a better shock, there not really much use considering it cost 200 gbp to rebuild each corner... Kind of pointless to have suspension that costs too much to repair..
You could get your 1 BC coilover rebuilt 3-4 times for the price of getting 1 Tein repaired once lol