Java cannot do become:, so, that's not going to be a "real" smalltalk.
I do work w/ Java & Scala on a project.
First, JAR hell -> productivity killer
Second, lots of infrastructure needed: IDE, Maven, Artifactory, ... -> another productivity killer
Long story short: prototype the thing in Pharo and if good enough, run it there.
I've done that for one project of late. Net resut: it takes 5x the engineers and 3x the time to do the same in X than with Pharo.
If you want to do Java/Scala, by all means, go there. But why the hell is this going to be so important?
Read��
for lots of pro/cons arguments on other languages (which do not give a shit about Java mean you).
Phil