I finally decided to move forward and had the Basepump CB 1500 water powered backup sump pump system installed. I am very happy with it. I did some testing and it appears to be able to pump close to 2000 gallons per hour.
Rather than install it myself, I chose Sunkel plumbing, which I found on the distributor list on the manufacturer's website. The installation went smoothly. I chose to have the discharge routed directly outside rather than hooking into the existing discharge pipe. I did this to prevent a blockage of the existing discharge from preventing the water backup pump from working. I know two people who had their basements flood due to their discharge pipe being blocked and I did not want that to happen to me.
I'll post some pictures of the installation soon.
