ORIGINAL: da Rock
Why not use the OS46LA ??
All the engines you've listed are really in the same price range, $55-$70. The difference from cheapest to most expensive wouldn't stop anyone from racing if they wanted to race. And the $68 for the 46LA isn't the most expensive anyway. And the motor mount holes are as wide as the 40LAs' you've been using so it'd be possible to swap this one in on existing planes with only a bit of work, not a major amount.
People are used to handling the 40LA and this won't be any different. Plus the power difference isn't going to be tremendously less or a bunch more.
And let 'em run existing planes and whatever 40LAs are still kicking.
Those are okay but they are going to be discontinued when they sell all the Os 46 la's they have in stock.