Dear Lado
in any case: there is enough difference between ECC 5 ECC 6. ECC 6.0: to my knowledge: now we have EnhPack 8 in place.
The impact of an upgrade depends on the EHS functionality used so far. If you have used only EHS IHS: the impact is very low. If you have used EHS BD, PS; DG ... IMpact is bigger (even not activating something).
C.B.