weight is def an advantage, just depends on how much weight.
I went to a mat with a co-worker thats around 210 and hes a daily gym guy. I'm 150-155 pounds. We were even on our feet, he couldn't take me down based on feet work. I am very confident on my feet
But I had a hard time taking him down based on his weight on my back when he was sprawling. I had good position, but weight does make a difference.
on top position, I am able to hold my own. On bottom position, certainly harder with bigger weight