Ruby 2 is almost dropin replacement for Ruby 1.9.3. so upgrading should be easy & backwards compatible with following exceptions

    Incompatibility
    There are five notable incompatibilities we know of:

    The default encoding for ruby scripts is now UTF-8     [#6679]. Some people report that it affects existing     programs, such as some benchmark programs becoming very slow [ruby-dev:46547].

    Iconv was removed, which had already been deprecated when M17N was introduced in ruby 1.9. Use String#encode, etc. instead.

    There is ABI breakage [ruby-core:48984]. We think that normal users can/should just reinstall extension libraries. You should be aware: DO NOT COPY .so OR .bundle FILES FROM 1.9.

    #lines, #chars, #codepoints, #bytes now returns an Array instead of an Enumerator [#6670]. This change allows you to avoid the common idiom "lines.to_a". Use #each_line, etc. to get an Enumerator.

    Object#inspect does always return a string like #<ClassName:0x…> instead of delegating to #to_s. [#2152]

    NEWS: https://www.ruby-lang.org/en/news/2013/02/24/ruby-2-0-0-p0-is-released/

I would encourage you to try out ruby2 today, you will be surprised how easy the upgrading process is. Plus, your app will run 20% faster due to performance improvements