This is a great idea Bex, I am a firm advocate of weighing my only concern is if you wipe off the previous weight and write the new weight you won't be able to see a pattern. My pigs have there own pad for weights, and are weighed every week, for example if they lost 10grams on Tuesday, that wouldn't be a problem, but they could have lost 10 gram the last 3 weeks and I may miss it if I didn't have on record all their previous weights.
However weighing your pigs weekly and tracking their weights is a brilliant idea and anybody that doesn't do it should consider starting I find it invaluable, and I can spot illnesses very quickly!
x