Should I use SIPs for my extension?

I am no expert, and it's a long time since you asked the question, so I expect you know all the answers by now, BUT the experiences of our own extension project - where we, too, thought of using SIPS - tells me that trying the marry the SIPS panels to the old elevations would probably be a nightmare. Unless the SIPS manufacturers have a way of overcoming the problem - ie by treating the extension as a completely separate unit, somehow, build hard-up against the original house.....