One thing to keep in mind is the sound of the rubber pads. The drums and cymbals are not perfectly quiet. There is the tapping sound on the rubber.
I had forgotten how loud an acoustic set was until I was sitting behind my friend's full blown kit (8 toms). Between the cymbals and drums my ears were ringing! Sound proof rooms are definitely a good option.
Another option with Roland electronic drums is the expansion packs you can purchase from V Expressions Ltd (vexpressionsltd.com). These are custom kits that bring an improved sound to Roland drums. For a $30 investment they are worthwhile.