Maxi Puppy 3000 vs Whale Gulper?

[Dr. Sea]

I went to buy a Jabsco Maxi Puppy 3000 to replace the old one being used for a bilge pump on my boat. I thought the retailer was joking when he said $529 for it. I went back to the boat and installed a spare Whale Gulper instead. Three questions:

1. Is there any important reason to not use a Whale Gulper for a bilge pump?

2. What is so special about a Maxi Puppy to cost that much? Even at discount shops in the USA it costs twice as much as a Whale Gulper.

3. Does anyone have a strong recommendation for an automatic bilge pump? I have a fairly large and deep bilge so it would need to have fairly large capacity. My system is 24v. The Maxi Puppy is rated for up to 10 gallons per minute.