Just remembered a project I did some years ago, this started just as one loss in weight for feeding uncooked rice at a given weight (tonnes/hr), however, it was expanded to do the same for one of the other ingredients, this was a continuous feed system the rice bags sat on two hangars with load cells & fed into a sieve & then blown into a continuous rotary cooker, only one bag would be active (one in use other for instantaneous changeover), this was controlled by a PID loop (cannot go into the mechanics of how the feed was controlled as may still be a secret), this was an existing system not done by me, however, I modified it to incorporate load cells for a loss in weight of one of the other ingredients, this too had a PID it worked extremely well, the system would stop for short periods (not the cooker just the feeds).
Over time, we trended the feed systems along with the buying dept came up with the typical accuracy of the blend, this turned out to be within about 1.5%.
The only problems I think you may have is if there is vibration from the system that could affect the load cells may cause fluctuations in loss in weight but can be smoothed out & the speed of recovery of a PID on a start.