I am experiencing a similar issue on my 09 FWD with 45k miles on it. I do not think it is the engine mounts, because I have tried the brake hold and mash the gas it makes no noise.
What I am seeing/feeling is when taking off from a non complete stop, rolling stop you can call it, I feel a clunk in the floor and through the steering wheel. The Nissan dealer thinks it might be the torque converter in the transmission but I am not buying it.
2009 Murano SL in Platinum Graphite Metallic