A solid Racket VM and GUI for Android and iOS apps would be awesome.
In the interim, two reasons why a solution using an R5RS Scheme might work well for a lot of Racket people:
* Lots of code written in Racket can actually be written in R5RS almost as well. (Example: say that the secret sauce of your app was a symbolic planner or inference engine. That library might well have been written entirely in R5RS in the first place, even if you only intended to use it with Racket. So that key library source code could be shared between your Racket programs and your LambdaNative program. And you'd probably do most of the other parts of the app using LambdaNative directly, since they're probably irrelevant to your Racket programs anyway.) And there are a few different viable ways to close the gap even more.
* Much of a Racket programmer's skill transfers over easily to R5RS. (Idiomatic Racket programming is mostly idiomatic Scheme programming, IMHO.)
Incidentally, a decade ago, I switched from portable R5RS to Racket (then called PLT Scheme) exclusively, while keeping Gambit and Kawa especially as backup alternatives for special situations. I think I actually suspected that I'd need one of my backups before now. Racket continues to perform very well for most all purposes.
Neil V. ____________________ Racket Users list: http://lists.racket-lang.org/users