Hang on a moment. If there is "differential" pricing I can see that as potentially irritating for end users and may infact be counterproductive. What if User A says to User B "Oh, I got my Select for £50" - "Whatttt!!! I paid £100, da*n ROL I'll never buy off them again...."
Then there's the notion that programmers will use Select features and give "error messages" to users telling them Select is required (now for users whose machines *can* be upgraded this will be mildly irritating - but for users whose machines can't be (e.g., Iyonix) it'll make them see red!). Whipping the end user to hop through ROL defined upgrade "hoops" is very Microsoftesque and IMHO illbecomes this platform.
As jmb pointed out there's the lack of documentation (an impediment to developers) then there's the lack of ubiquity (how many people have select - obviously not that many if ROL has the time to talk to people *individually*). This whole tact I am sad to say looks incompletely thought through and has an almost pathetic despiration about it.
The leading RO version is 3.7, followed by 4.0X and 5.XX that's what developers are aiming at. If RO wants them to aim at Select - then Select needs to get (a). More commonly used (b). More publically documented and (c). available on the platforms developers use rather than the ones ROL *wants* them to use.