I asked the same question when I went to a gear drive and 8 GPM,..the pump weighing 40 lbs itself. I was also told not to worry about the weight issue on the gear box,... by very credible sources and I listened to them and haven't had an issue. I still look sometimes though,Ha,Ha,..
I was also told by one of the members here about snapping bolts,..he told me to use Grade 8 bolts. I did,..and I will replace them every season,.probably overkill but it's very cheap insurance.
Jeff