Just a guess, but they were never a big seller, relatively speaking. IP is a big company. They built 188 IP 38 (monohull), 139 IP 40's, etc. 41 cats spread over six years was probably not profitable enough for them to justify continuing a line that was so different from the rest of their models.
I would also say that despite Kanter's praises for them, they are still a strange boat. Having seen one in person, they just "look" weird. Not enough of a cat look, but clearly not a mono, either. Frankly, they look more like a small houseboat. While that might have nothing to do with their actual sailing or living performance, it does have a lot to do with market acceptance and sales.
Observations are gold; hypotheses, silver; and conclusions, bronze.
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Everyone is entitled to their own opinion, but not their own facts.--Daniel Patrick Moynihan