Just fwiw. And of course there are some truly massive suburito. Although at some point I think it just gets silly.
I tend to agree with this. The problem with a massive suburito (or even just a 'large' one) will be that it's almost impossible to do good tanren with it because you'll constantly shift over into muscular arm and shoulder usage. I tend to do most of my suburi with my 3 lighter sticks and only use the heavy ones occasionally as a check that my internal-strength/suit is improving in manipulating them (i.e., a check to make sure I'm not bs'ing myself about my progress). Of course I'd have to note that someone once told me that Abe Seiseki swung a 40-odd pound suburito with regularity. More than I can comfortably do, for sure.