Take with a grain of salt as I'm an armchair grappler (meaning I watch a ton of material, but unfortunately don't train). I'd recommend watching Marcelo at absolute. Granted he's not a rubber guard player, but he taps much bigger men. IMO, I don't think I'd want to play RG on a guy if you can't do the technique right because of their size. Otherwise, roll with bigger guys and get a feel for the adjustments you'll need to make. But again, take what I say with a grain of salt.
Example: I used to be about 170 when I used to roll (garage style). I was more mobile, flexible, etc. My game was closed guard. I recently rolled (I'm 240lbs now...no not solid muscle; I wish), and I couldn't even close my guard around my oppenent. And my butterflies suck since my abs are weak as hell. Basically, I have to adjust my game. Where before my game was closed guard to frustrate and create openings, now, I can't even close my guard against these big boys. I'm gonna have to work on my lockdown and butterflies. Basically, my point is simple. Adjust your game plan. Tis all.
I understand what you guys are suggesting. I guess its all case by case though. I could see myself arm baring that Guy but more than likely getting slammed in the process. I think I was weary of that @ the time.
It was also suggested to me that the Guy ran a mean guillotine, so I was hesitant on my HG game. I also got caught up a little there and had to post on his hips. I'm just glad he didn't break my neck during the slam.