I did a brief search and it appears that Interboro is a NY domiciled company. AM Best has them rated as an "NR" which means "No Rating". They also have the outlook listed as "Not Applicable". Neither is necessarily a bad thing but it does throw up flags. However, here is a press release from the NY DOI where Interboro came out of rehabilitation in 2007.
http://www.ins.state.ny.us/press/2007/p0702221.htm
You will see in the article where they are NY's oldest insurance company "serving Long Island". You will also see where 70 jobs were saved. Small company. Personally I like small companies as long as they aren't spread too thin. If they are "balls to the walls" writing coastal exposures I'd run. If they are being really careful picking and choosing, they might very well be a viable option.
I gotta disclaim my next statement. If I am not mistaken, New York has a $500,000 guarantee fund that protects consumers if an insurance company goes into liquidation. It is illegal for an agent/broker to use the guarantee fund as a sales tool. That is why the disclaimer.
All that being said, I have been up to my azz in the NC Beach Plan issues that are hanging on us right now. But, that's a nother story.