It seems to me that if there are such huge deals on refurbs, then it might make sense to purchase the priciest Canon items this way, such as the superteles, or the 1 series bodies. Of course it's possible there isn't as much of a "deal" on these...
Aside from the 300mm 2.8 II, and the 400mm DO, they don't typically stock the super tele refurbs - they only started carrying the 300 around the middle of this year. Hopefully they'll be adding some of the others down the road.
The deal on those lenses is pretty good - the price on the 300mm, during this recent sale, was $4963 and you still get the 1 year warranty. They only had one in stock, though, and it sold out within the first minute of the sale starting. I believe it's the first time that lens was in stock during one of the % off sales.