Probably, but I think they really started to gain weight due to the safety stuff that the EU/US wanted adding in. An HPAS system will be heavier than a non-HPAS unit (it's a common mod among the MX5 lot), but I'm more concerned with the fact that they have to keep a mech unit in just in case the DBW system fails. That just seems counter productive to me.
The only EPAS system I'm really familiar with is the Porsche one, and whilst it didn't bother me at first at all, the more I drive the new range the more it puts me off. Probably a good thing really, else I'd only go and buy a Boxster tomorrow otherwise Need to try the GT3 really, but that'll never happen.