Scala vs GemStone/S
When comparing Scala vs GemStone/S, the Slant community recommends Scala for most people. In the question“What are the best server side programming languages?” Scala is ranked 8th while GemStone/S is ranked 28th. The most important reason people chose Scala is:
The immutable values make it perfect for working with concurrency
Specs
Ranked in these QuestionsQuestion Ranking
Pros

Pro Immutable values
The immutable values make it perfect for working with concurrency
Pro Multiparadigm
Scala supports both Functional and Object Oriented styles of programming. Beginners can learn both paradigms without having to learn a new language, and experts can switch between the two according to what best suits their needs at the time.
Pro Type inference
Scala offers type inference, which, while giving the same safety as Java's type system, allows programmers to focus on the code itself, rather than on updating type annotations.
Pro Compiles to JVM bytecode
Aside from Java itself, Scala is by far the most popular of the many JVM languages. If you're developing for Android, or a similar JVM-only platform, or otherwise need out-of-the-box cross-platform compatibility, but the performance of a compiled language, Scala is the way to go.
Pro Very good online courses
On coursera you can find great introduction to Scala by Martin Odersky.
Pro Type inference leads to a simpler syntax
Pro Expressive functional programming abstraction for reusable and safe code
Pro Scalable object-oriented persistence
Gemstone/S is a persistent object environment, capable of high performance database tasks.
Pro Free version even for commercial use
GemStone/S has very capable licenses for no cost that allow businesses to use it commercially for no cost.
Pro Extreme robustness, performance and flexibility
This product has a long line of evolution, guaranteeing all these qualities
Pro Smalltalk
Smalltalk is one of the most productive environments, which makes the hard things easy and the difficult, practical.
Pro Tightly related to Pharo Smalltalk
You can develop your Smalltalk projects on friendly Pharo and run them on the rock solid GemStone environment.
Pro Live debugging production errors
Never debug from textual traces anymore: do live debugging of saved stack traces for production errors
Cons

Con Can be intimidating for beginners
Scala is an industrial language. It brings functional programming to the JVM, but not with a "start small and grow the language" perspective, but rather a very powerful language for professional programmers.
Con Way too complex for beginners
Even for seasoned programmers it's a difficult language.
Con Static type system inherits cruft from Java
The type system is too complicated yet still less powerful than Haskell's.
Con Vendor lock-in
The environment is unique and you easily become very dependent on what it has to offer, while there is no alternative vendor to switch to.
Con The runtime environment is essentially free, but not open source.
