Jinzo,
I have used a GH snowblower on my 1992 612 from the begining with nothing but good results. It works in 2" snow to 20" snow. I have even had great success with deep drifted snow once I have gotten through the first pass, I added drift cutters off an old Bolens tractor mount blower I used to use, that has helped me cut through 48" drifts. The only draw back I have ever encountered is snow gettng up intothe PTO drive belt and the orbital drive belt, the new direct drive pumps would help with that.