The action on the Roland G70 is NOT the same as the XP series (yuck!). To my knowledge, the only models with exactly the same action are the G800, G1000, VA76 and the A70 controller. The latter is what I would highly recommend if you can find a good condition one on Ebay.
Up to 8 zones and more controllers than you can shake a stick at!

I have said this in the past, but I consider the G70's action (plus the above mentioned) the finest plastic action on the planet! Enough weight and feel for piano work, and smooth enough for organ licks and smears.

A BIG plus with the G70 is the engine is now fast enough that playing the keyboard feels very 'connected' to the sound, something that many keyboards don't. Speed of triggering the sound (the keyboards 'latency' if you will) makes a huge difference to how responsive it feels. Also layers seem to trigger simultaneously now, whereas most previous generation keyboards tended to 'flam' just a little bit on big chords.

Anyway, a BIG thumbs up for the A70 for what you are looking for (but not light!).