I have used Insinkerators since I was kid and my Dad installed one.
In 1995, I had a multi-stage Insinkerator installed over a septic tank (sized for a four bedroom - 3 bath home) for the first time. Never had an issue. In 2006 I had two multi-stage Insinkerators installed over a septic system (sized for a 5BR - 4Ba home) and have never had an issue.
I purchased this one for a small river cottage with a ten year old septic system which was pumped and inspected in May of this year.
It is quieter than any I have had before and it is fast and efficient. I expect no issues with this one - the 10 and 20 year old ones are still performing like new.
Buy one!