For realism, this would be your best. If portability is not an issue you could look into the Clavinova CLP range, specifically the CLP370 or 380 or perhaps the older CLP280. These would be furniture type digital pianos - not portable.
You could also try out the Yamaha CP-300 - not very heavy but I think you would find it hard to find any digital piano that has a very heavy action.
From Roland, you could look into the FP-8 which will have an action that is heavier than the RD-300GX but perhaps not significantly so in order to make a big enough difference.
I own both and prefer the CP-300. The CP-33 I use for throwing in the back of my car.