My "Heavy Putter" with all the head weights installed, and grip counter weights, weighs in at 900 grams according to the manufacturer. It's from around 2005, I think. Not sure.
I went to the Heavy Putter due to damage to my 300 gram putter of many years.
It took a while to get use to the added weight, but once I got use to it, my putting was as good, if not better than before the change .