So where's the 450sm everybody's been clamoring for?

It's not coming. Don't go there. I made the mistake of trying to post several reasons why a WR450X can't have 26,000 mile valve intervals and 50 hp and weigh 300 pounds street legal all costing close to $6,000. I used the WR450F -- that has neither 26,000 mile valve intervals nor 50 hp nor a sub-$7,000 price tag -- as an example.
The typical response was, well, Yamaha could do it if they wanted to.