Great point Tim, that is true, the system is of course far more dynamic, and you would need to account for the ability to adjust for things such as a swinging/seaming ball, deliveries of a different length (eg full vs short). It is very different to try and drive with a heavier than usual bat vs playing the hook and the pull for example.
I think it comes down to experimentation. In my opinion, if someone wanted to try a heavier bat, maybe go for something relatively cheap eg a Grade 3 or so bat, and if you find you get on well, then maybe migrate to that weight on a full scale basis.
One last thing to also note, a heavier bat will also likely affect your stamina or endurance over a long innings. Hence while you may get on well in say a 20/20 where you only have to bat for 5-10 overs or so usually, if you were playing a 60 over match or something, you may find it affecting your game negatively over a longer innings.