the rebate thingy is awesome, we got the old part of the house done a few months ago. Its quite large so our out of pocket costs were a little bit more AND we could only claim the renters one ($1000) but we got the R4 insulation. If we were the owners we would have been out of pocket by $100.

To be completely honest it hasn't made too much of a difference that we can notice - Summer will be the best measure though, old homes in winter seem to be cold no matter what