Hello Andres,
>> This patch adds an option to change the default tuple size, so that this can
>> be tested easily.
>
> I don't think it's beneficial to put this into pgbench. There really
> isn't a relevant benefit over using a custom script here.
The scripts to run are the standard ones. The difference is in the 
*initialization* phase (-i), namely the filler attribute size. There is no 
custom script for initialization in pgbench, so ISTM that this argument 
does not apply here.
-- 
Fabien.